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Poster Session I - University of Ulsan

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The 9th Korea-Japan Conference on<br />

Ferroelectrics<br />

KJC-FE09<br />

<strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong>, Korea<br />

August 7-10, 2012


Committee members <strong>of</strong> KJC-FE09<br />

Advisory Committee<br />

Organization<br />

Committee<br />

Sook-Il Kwun * Seoul National <strong>University</strong><br />

Sunggi Baik Pohang <strong>University</strong> <strong>of</strong> Science and Technology<br />

Sung Ho Cho Korea <strong>University</strong><br />

Min Su Jang Pusan National <strong>University</strong><br />

Jong-Jean Kim<br />

Korea Advanced Institute <strong>of</strong> Science and<br />

Technology<br />

Gwang Seo Park Sogang <strong>University</strong><br />

Yoshihiro<br />

Ishibashi<br />

Kyushu <strong>University</strong><br />

Yukio Noda Tohoku <strong>University</strong><br />

Masanori<br />

Okuyama<br />

Osaka <strong>University</strong><br />

Masaru Shimizu <strong>University</strong> <strong>of</strong> Hyogo<br />

Masaharu<br />

Tokunaga<br />

Hokkaido <strong>University</strong><br />

Toshirou Yagi Hokkaido <strong>University</strong><br />

Ill Won Kim * <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong><br />

Hyun Myung Jang Pohang <strong>University</strong> <strong>of</strong> Science and Technology<br />

Yoon Hee Jeong Pohang <strong>University</strong> <strong>of</strong> Science and Technology<br />

Jaichan Lee Sungkyunkwan <strong>University</strong><br />

Tae Won Noh Seoul National <strong>University</strong><br />

Chul Hong Park Pusan National <strong>University</strong><br />

Yoshihiro Kuroiwa Hiroshima <strong>University</strong><br />

Yukikuni Akishige Shimane <strong>University</strong><br />

Yasuo Cho Tohoku <strong>University</strong><br />

Seiji Kojima <strong>University</strong> <strong>of</strong> Tsukuba<br />

Shigeo Mori Osaka Prefecture <strong>University</strong><br />

Hitoshi Tabata The <strong>University</strong> <strong>of</strong> Tokyo


Committee members <strong>of</strong> KJC-FE09<br />

Program Committee<br />

Publication Committee<br />

Local Committee<br />

Sungkyun Park * Pusan National <strong>University</strong><br />

Sang Don Bu Chonbuk National <strong>University</strong><br />

Myong Pyo Chun KICET<br />

Cheol Seong Hwang Seoul National <strong>University</strong><br />

Sang-Su Kim Changwon National <strong>University</strong><br />

Sang-Woo Kim Sungkyunkwan <strong>University</strong><br />

Hee Young Lee Yeungnam <strong>University</strong><br />

Yunsang Lee Soongsil <strong>University</strong><br />

Kazumi Kato AIST<br />

Norifumi Fujimura Osaka Prefecture <strong>University</strong><br />

Naoshi Ikeda Okayama <strong>University</strong><br />

Makoto Iwata Nagoya Institute Technology<br />

Hiroki Moriwake JFCC<br />

Yuji Noguchi The <strong>University</strong> <strong>of</strong> Tokyo<br />

Yoon-Hwae Hwang * Pusan National <strong>University</strong><br />

Jai Seok Ahn Pusan National <strong>University</strong><br />

DaeYong Jeong Myongji <strong>University</strong><br />

Jong-Sook Lee Chonnam National <strong>University</strong><br />

Tae Kwon Song Changwon National <strong>University</strong><br />

Ken-ichi Kakimoto Nagoya Institute Technology<br />

Hironori Fujisawa <strong>University</strong> <strong>of</strong> Hyogo<br />

Hiroyuki Kimura Tohoku <strong>University</strong><br />

Chikako Moriyoshi Hiroshima <strong>University</strong><br />

Minoru Noda Kyoto Institute Technology<br />

Satoshi Wada <strong>University</strong> <strong>of</strong> Yamanashi<br />

Young-Han Shin *<br />

Chang Won Ahn<br />

Shinuk Cho<br />

Hye-Jung Kim<br />

Yong Soo Kim<br />

Jae-Shin Lee<br />

<strong>University</strong> <strong>of</strong> <strong>Ulsan</strong><br />

* Chairs <strong>of</strong> the committees


Welcome to KJC-FE09<br />

We are pleased to announce that the 9th Korea-Japan Conference on<br />

Ferroelectrics (KJC-FE09) will be held in <strong>Ulsan</strong>, Korea from the 7th<br />

(Tuesday) to the 10th (Friday) <strong>of</strong> August, 2012. The conference will be<br />

hosted by <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong> with the collaboration <strong>of</strong> the Research<br />

Center for Dielectric and Advanced Matter Physics at Pusan<br />

National <strong>University</strong>.<br />

The conference has been continued with the successful previous meetings,<br />

held first at Pusan National <strong>University</strong> in 1994, followed by Hokkaido<br />

<strong>University</strong> in 1996, Kyongju TEMF Hotel in 1999, Osaka <strong>University</strong> in<br />

2002, Seoul National <strong>University</strong> in 2004, Tohoku <strong>University</strong> in 2006,<br />

Cheju National <strong>University</strong> in 2008, and Egret Himeji in 2010.<br />

The conference will cover all areas <strong>of</strong> ferroelectrics in both theories and<br />

experiments, ranging from fundamentals to applications. The primary goal<br />

<strong>of</strong> the conference is to promote binational cooperation between Korean and<br />

Japanese scientists and to exchange new ideas and results <strong>of</strong> ferroelectrics<br />

research.<br />

Presentations, oral and poster, <strong>of</strong> original research on ferroelectrics and<br />

related materials are cordially invited. Students and young researchers are<br />

particularly encouraged to participate and share the spirit <strong>of</strong> the conference.<br />

Conference chairs, Ill Won Kim and Yoshihiro Kuroiwa


S p o n s o r s<br />

<strong>University</strong> <strong>of</strong> <strong>Ulsan</strong><br />

http://www.ulsan.ac.kr<br />

Energy Harvest-Storage Research Center<br />

(EHSRC) at <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong><br />

http://phys.ulsan.ac.kr<br />

The Institute for Basic Sciences at<br />

Changwon National <strong>University</strong><br />

http://portal.changwon.ac.kr/home/sbasic<br />

NEXTRON<br />

http://www.nextron.co.kr<br />

AMS KOREA<br />

http://www.amskorea.net


Campus Map <strong>of</strong> <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>


The detailed map around the International Building<br />

The route between the International Building and the Heasong Hall<br />

The route between the MainGate and the International Building


Floor plans <strong>of</strong> the International Building<br />

101<br />

Oral<br />

<strong>Session</strong>s<br />

<strong>Poster</strong><br />

<strong>Session</strong>s I & II<br />

Gallery


Floor plan <strong>of</strong> the Mugeo Dormitory


August 7<br />

(Tue)<br />

August 8<br />

(Wed)<br />

KJC-FE09 Program Outline<br />

<strong>Session</strong> Hour<br />

15:00-17:30<br />

Type Speaker<br />

17:30-19:00<br />

Chair: Sungkyun Park and Kazumi Kato<br />

Opening 09:00-09:20<br />

Chair: Hironori Fujisawa<br />

Plenary talk I 09:20-10:00 Plenary Sang-Wook Cheong<br />

Multiferroics<br />

C<strong>of</strong>fee break 10:55-11:10<br />

Nano-structured<br />

ferroelectrics<br />

Lunch break 12:15-13:30<br />

Ferroelectric thin<br />

films<br />

C<strong>of</strong>fee break 15:00-15:15<br />

Lead-free<br />

piezoelectrics<br />

10:00-10:25 Invited Chan-Ho Yang<br />

10:25-10:40 Contributed Shigeo Mori<br />

10:40-10:55 Contributed Ran Hee Sin<br />

Chair: Yoon Hwae Hwang<br />

11:10-11:35 Invited Minoru Osada<br />

11:35-12:00 Invited Suck Won Hong<br />

12:00-12:15 Contributed Kazumi Kato<br />

Chair: Norifumi Fujimura<br />

13:30-13:55 Invited Cheolmin Park<br />

13:55-14:20 Invited Tatsuya Shimoda<br />

14:20-14:45 Invited Tae Won Noh<br />

14:45-15:00 Contributed Min Hyuk Park<br />

Chair: Cheol Seong Hwang<br />

15:15-15:40 Invited Hiroshi Funakubo<br />

15:40-16:05 Invited Jae-Shin Lee<br />

16:05-16:30 Invited Seiji Yamazoe<br />

16:30-16:45 Contributed John G. Fisher<br />

16:45-17:00 Contributed Ken-ichi Kakimoto<br />

Chair: Hiroki Taniguchi and Sang Don Bu<br />

<strong>Poster</strong> session I 17:00-18:30<br />

Dinner 18:30-20:00


August 9<br />

(Thu)<br />

August 10<br />

(Fri)<br />

KJC-FE09 Program Outline<br />

<strong>Session</strong> Hour Type Speaker<br />

Chair: Yuji Noguchi<br />

Applications<br />

C<strong>of</strong>fee break 10:15-10:30<br />

<strong>Poster</strong> session II 10:30-12:00<br />

09:00-09:25 Invited Masanori Ueda<br />

09:25-09:50 Invited Soon-Gil Yoon<br />

09:50-10:15 Invited Yukihiro Kaneko<br />

Chair: Jae-Hyeon Ko and Kenji Tsuda<br />

Lunch break 12:00-13:30<br />

Chair: Jaichan Lee<br />

Plenary talk II 13:30-14:10 Plenary Yoshiaki Uesu<br />

Superlattices<br />

Photo time 15:00-15:10<br />

Excursion 15:10-18:00<br />

Break 18:00-18:30<br />

Banquet 18:30-21:00<br />

Ferroelectric phase<br />

transitions<br />

14:10-14:35 Invited Ji Won Seo<br />

14:35-15:00 Invited Ji Young Jo<br />

Chair: Chikako Moriyoshi<br />

09:00-09:25 Invited Hiroki Taniguchi<br />

09:25-09:50 Invited Jae-Hyeon Ko<br />

09:50-10:15 Invited Kenji Tsuda<br />

Domain dynamics 10:15-10:40 Invited Yukio Sato<br />

C<strong>of</strong>fee break 10:40-10:55<br />

Ceramics and nano<br />

particles<br />

Closing 12:00-12:10<br />

Chair: Tae Kwon Song<br />

10:55-11:20 Invited Tae-Sik Yoon<br />

11:20-11:45 Invited Muneyasu Suzuki<br />

11:45-12:00 Contributed Ali Hussain


7 th Aug. (Tue)<br />

15:00 ~ 17:00<br />

17:30 ~ 19:00<br />

8 th Aug. (Wed)<br />

Program <strong>of</strong> KJC-FE09<br />

Registration and Dormitory allocation<br />

(1F, International Building)<br />

Welcome Reception<br />

(Room 411, 4F, International Building)<br />

(<strong>Session</strong> Chair : Sungkyun Park & Kazumi Kato)<br />

09:00 ~ 09:20 Opening (Room 101, 1F, International Building)<br />

09:20 ~ 10:00<br />

Plenary<br />

PL-1 Sang-Wook Cheong (Rutgers <strong>University</strong>)<br />

Multiferroic vortex network with Z2×Z3 symmetry<br />

(<strong>Session</strong> Chair : Hironori Fujisawa)<br />

Multiferroics (<strong>Session</strong> Chair : Hironori Fujisawa)<br />

I-1 Chan-Ho Yang (KAIST)<br />

10:00 ~ 10:25 Concurrent transition <strong>of</strong> magnetic and ferroelectric order near room<br />

temperature<br />

10:25 ~ 10:40<br />

10:40 ~ 10:55<br />

10:55 ~ 11:10 C<strong>of</strong>fee break<br />

C-1 S. Mori (Osaka Prefecture <strong>University</strong>)<br />

Charge ordering phenomena in YFe2O4<br />

C-2 Ran Hee Shin (Ewha Womans <strong>University</strong>)<br />

Ferroelectric polarization driven by divalent ion-substitution into<br />

epitaxial gallium iron oxide thin films<br />

Nano-structured ferroelectrics (<strong>Session</strong> Chair : Yoon Hwae Hwang)<br />

11:10 ~ 11:35<br />

11:35 ~ 12:00<br />

12:00 ~ 12:15<br />

12:15 ~ 13:30 Lunch break<br />

I-2 Minoru Osada (National Institute for Materials Science)<br />

Two-Dimensional Oxide Nanosheets: New Solution to Nanodielectronics<br />

I-3 Suck Won Hong (Pusan National. <strong>University</strong>)<br />

Two-faced periodic arrays <strong>of</strong> ZnO nanorods based on flexible grapheneplastic<br />

substrate for energy harvesting<br />

C-3 Kazumi Kato (National Institute <strong>of</strong> Advanced Industrial Science and Technology)<br />

Capabilities <strong>of</strong> BaTiO3 and SrTiO3 Nanocube Self-Assemblies


8 th Aug. (Wed)<br />

Ferroelectric thin films (<strong>Session</strong> Chair : Norifumi Fujimura)<br />

13:30 ~ 13:55<br />

13:55 ~ 14:20<br />

14:20 ~ 14:45<br />

14:45 ~ 15:00<br />

15:00 ~ 15:15 C<strong>of</strong>fee break<br />

I-4 Cheol Min Park (Yonsei <strong>University</strong>)<br />

Controlled hierarchical nanostructures <strong>of</strong> thin ferroelectric polymer films<br />

for non-volatile memory applications<br />

I-5 Tatsuya Shimoda (Japan Advanced Institute <strong>of</strong> Science and Technology)<br />

Research topics about solution derived PZT<br />

I-6 Tae Won Noh (Seoul National <strong>University</strong>)<br />

Tuning ferroelectric properties <strong>of</strong> epitaxial oxide thin films<br />

C-4 Min Hyuk Park (Seoul National <strong>University</strong>)<br />

Examination on the ferroelectricity in HfxZr1-xO2 thin film<br />

Lead-free piezoelectric (<strong>Session</strong> Chair : Cheol Seong Hwang)<br />

15:15 ~ 15:40<br />

15:40 ~ 16:05<br />

16:05 ~ 16:30<br />

16:30 ~ 16:45<br />

16:45 ~ 17:00<br />

I-7 Hiroshi Funakubo (Tokyo Institute <strong>of</strong> Technology)<br />

Low temperature synthesis <strong>of</strong> epitaxial and fiber-textured (K,Na)NbO3<br />

thick films grown by hydrothermal method<br />

I-8 Jae-Shin Lee (<strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>)<br />

Possible mechanism <strong>of</strong> giant strain in BNT-based lead-free ceramics<br />

I-9 Seiji Yamazoe (The <strong>University</strong> <strong>of</strong> Tokyo)<br />

Crystallographic and domain structures <strong>of</strong> ferroelectric (Li,Na)NbO3<br />

films fabricated by a pulsed laser deposition<br />

C-5 John G. Fisher (Chonnam National <strong>University</strong>)<br />

Sintering <strong>of</strong> (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead–free piezoelectric ceramics<br />

C-6 Ken-ichi Kakimoto (Nagoya Institute <strong>of</strong> Technology)<br />

Interfacial reactions for Co-fired Ni-(Na,K)NbO3 piezoceramics<br />

(<strong>Session</strong> Chair : Hiroki Taniguchi & Sang Don Bu)<br />

17:00 ~ 18:30 <strong>Poster</strong> sesstion I (Gallery, 2F, International Building)<br />

18:30 ~ 20:00 Dinner


9 th Aug. (Thu)<br />

Applications (<strong>Session</strong> Chair : Yuji Noguchi)<br />

I-10 Masanori Ueda (TAIYO YUDEN Co., Ltd.)<br />

09:00 ~ 09:25 Radio-frequency surface acoustic and bulk acoustic wave devices with<br />

high performances and unique structures<br />

I-11 Soon-Gil Yoon (Chungnam National <strong>University</strong>)<br />

09:25 ~ 09:50 Realization <strong>of</strong> transparent and flexible capacitors using reliable graphene<br />

electrode<br />

I-12 Yukihiro Kaneko (Panasonic Corporation)<br />

09:50 ~ 10:15 Recent progress <strong>of</strong> ferroelectric-gate field-effect transistor based on an<br />

oxide heterostructure<br />

10:15 ~ 10:30 C<strong>of</strong>fee break<br />

(<strong>Session</strong> Chair :Jae-Hyeon Ko & Kenji Tsuda)<br />

10:30 ~ 12:00 <strong>Poster</strong> session II (Gallery, 2F, International Building)<br />

12:00 ~ 13:30 Lunch break<br />

13:30 ~ 14:10<br />

Plenary<br />

PL-2 Yoshiaki Uesu (Waseda <strong>University</strong>)<br />

SHG microscope revisited<br />

(<strong>Session</strong> Chair : Jaichan Lee)<br />

Superlattices (<strong>Session</strong> Chair : Jaichan Lee)<br />

I-13 Ji Won Seo (Sungkyunkwan <strong>University</strong>)<br />

14:10 ~ 14:35 Ferroelectricity and magnetoelectric coupling in superlattices composed<br />

<strong>of</strong> non-ferroic components<br />

14:35 ~ 15:00<br />

15:00 ~ 15:10 Photo time<br />

15:10 ~ 18:00 Excursion<br />

18:00 ~ 18:30 Break<br />

18:30 ~ 21:00 Banquet<br />

I-14 Ji Young Jo (Gwangju Institute <strong>of</strong> Science and Technology)<br />

In-situ X-ray nanodiffraction <strong>of</strong> ferroelectric heterostructures


10 th Aug. (Fri)<br />

Ferroelectric phase transitions (<strong>Session</strong> Chair : Chikako Moriyoshi)<br />

09:00 ~ 09:25<br />

I-15 Hiroki Taniguchi (Tokyo Institute <strong>of</strong> Technology)<br />

Effect <strong>of</strong> Ca-substitution on the ferroelectricity in CdTiO3<br />

I-16 Jae-Hyeon Ko (Hallym <strong>University</strong>)<br />

09:25 ~ 09:50 Phase transition behaviors <strong>of</strong> PbZr1-xTixO3 single crystals as revealed by<br />

elastic anomalies and central peaks<br />

I-17 Kenji Tsuda (Tohoku <strong>University</strong>)<br />

09:50 ~ 10:15 Study <strong>of</strong> local structural fluctuations in ferroelectric BaTiO3 using<br />

convergent-beam electron diffraction<br />

Domain dynamics (<strong>Session</strong> Chair : Chikako Moriyoshi)<br />

I-18 Yukio Sato (The <strong>University</strong> <strong>of</strong> Tokyo)<br />

10:15 ~ 10:40 Domain response by electric fields in PMN-PT: An in-situ transmission<br />

electron microscopy study<br />

10:40 ~ 10:55 C<strong>of</strong>fee break<br />

Ceramics and nanoparticles (<strong>Session</strong> Chair :Tae Kwon Song)<br />

10:55 ~ 11:20<br />

11:20 ~ 11:45<br />

11:45 ~ 12:00<br />

12:00 ~ 12:10 Closing<br />

I-19 Tae-Sik Yoon (Myongji <strong>University</strong>)<br />

Resistive switching characteristics <strong>of</strong> metal-oxide nanoparticle assembly<br />

I-20 Muneyasu Suzuki (National Institute <strong>of</strong> Advanced Industrial Science<br />

and Technology)<br />

Enhanced ferroelectric properties <strong>of</strong> bismuth layer-structured<br />

ferroelectric thick films obtained by aerosol deposition method<br />

C-7 A.Hussain (Changwon National <strong>University</strong>)<br />

Fabrication <strong>of</strong> lead-free textured (Na0.53K0.47)(Nb0.55Ta0.45)O3 ceramics by<br />

reactive templated grain growth using NaNbO3 templates


<strong>Poster</strong> <strong>Session</strong> I (August 8, 17:00~18:30)<br />

Number Presenter Title<br />

P-1 Seong Su Jeong<br />

Increasing torque <strong>of</strong> one touch point ultrasonic linear motor by using multilayer<br />

ceramics<br />

P-2 Sung Sik Won Photocurrent behaviours <strong>of</strong> Pt/BNT/Pt and Pt/NKBiT/Pt capacitors<br />

P-3 Won Seok Woo<br />

P-4 Sang-Joon Park<br />

Photovoltaic effect <strong>of</strong> (Na0.82K 0.18) 0.5Bi 4.5Ti 4O 15 thin film with Pt and ITO top<br />

electrodes<br />

Control <strong>of</strong> oxygen vacancies by plasma enhanced atomic layer deposition (PEALD) <strong>of</strong><br />

TiO 2 for memristors<br />

P-5 Seung Eon Moon Piezoelectric energy scavenger based on PZT LTCC cantilever<br />

P-6 Byung Kil Yun Lead-free alkaline niobates nanostructures for piezoelectric nanogenerators<br />

P-7 Yu Jin Kim Transient negative capacitance in domain wall <strong>of</strong> ferroelectric thin films<br />

P-8 Shotaro Ishikawa<br />

P-9 Kohei Tsuchida<br />

P-10 Yeong Jae Shin<br />

P-11 Jung Min Park<br />

P-12 Sang Mo Yang<br />

Enhanced dielectric and piezoelectric properties <strong>of</strong> BaTiO3-based single crystals by<br />

defect-polarization control<br />

Influence <strong>of</strong> 60 o domain structure on orthorhombic niobate-based piezoelectric<br />

property<br />

Nanoscale visualization <strong>of</strong> domain wall pinning process as the origin <strong>of</strong> polarization<br />

fatigue<br />

Preparation <strong>of</strong> Epitaxial BiFeO3 Thin Films on La-SrTiO 3 Substrate by Magnetic-<br />

Field-Assisted Pulsed Laser Deposition<br />

Equilateral triangle closure domains in (111)-oriented epitaxial PbZr0.35Ti 0.65O 3 thin<br />

films<br />

P-13 Han Joon Kim Effect <strong>of</strong> Composition on the ferroelectric properties <strong>of</strong> Hf xZr 1-xO 2 thin film<br />

P-14 H. I. Choi Phase effect <strong>of</strong> the polycrystalline BiFeO 3 thin film by puled laser deposition<br />

P-15 Myang Hwan Lee The role <strong>of</strong> defect-dipole in BiFeO 3 thin films<br />

P-16 Byung Chul Jeon Flexoelectric Reversal <strong>of</strong> Polarization in Epitaxial BiFeO 3 Films<br />

P-17 Hyeon Jun Lee Morphology studies <strong>of</strong> poly(vinylidene fluoride-trifluoroethylene) copolymer films<br />

P-18 Song A Chae<br />

P-19 Sung Min Seo<br />

Measurement <strong>of</strong> transverse piezoelectric coefficient in the <strong>of</strong> Bi0.5(Na 0.82K 0.18) 0.5TiO 3<br />

lead-free films<br />

Electrical Properties <strong>of</strong> Compositionally Modulated Ferroelectric Pb(Zr,Ti)O3<br />

Multilayer Films<br />

P-20 Chang Jo Han Studies on photovoltaic effect <strong>of</strong> PZT thin film capacitors depending on Zr/Ti ratio<br />

P-21 Jin Kyu Han<br />

P-22 J.W. Kim<br />

P-23 T. Nakao<br />

P-24 Yu Yamamoto<br />

P-25 Yoshiki Yachi<br />

Effects <strong>of</strong> Concentration <strong>of</strong> Multi-walled Carbon Nanotube (MWCNT) on Electrical<br />

Properties <strong>of</strong> MWCNT�Pb(Zr0.52Ti 0.48)O 3 Composite Films<br />

Structure and electrical properties <strong>of</strong> Ba(Zrx,Ti1-x)O3 thin films by reactive sputtering<br />

method using metallic target<br />

Fabrication <strong>of</strong> Orientated (Na0.5K 0.5)NbO 3-BaZrO 3-(Bi 0.5Li 0.5)TiO 3 Thin Films on<br />

LaNiO3/SiO 2/Si Substrates by Pulsed Laser Deposition<br />

(Ag,Li)NbO3 thin films fabricated on (001), (110), and (111)SrTiO3 substrates by<br />

pulsed laser deposition<br />

The effect <strong>of</strong> crystallization process <strong>of</strong> P(VDF/TrFE) thin film on the ferroelectric<br />

properties


Number Presenter Title<br />

P-26 K.Wakazono Effects <strong>of</strong> La substitution for BiFeO 3 epitaxial thin films<br />

P-27 Thi Hinh Dinh<br />

P-28 J. S. Kim<br />

Phase transition behaviors in La-doped Bi1/2(Na 0.82K 0.18) 1/2TiO 3 lead-free piezoelectric<br />

ceramics<br />

Low Frequency Dielectric Dispersion and Conduction Behaviors <strong>of</strong> BaTiO3 modified<br />

Na0.5Bi 0.5TiO 3 Ferroelectric Ceramics<br />

P-29 Yuhji Tsujimi Low Frequency Optical Phonons in SrTiO 3 under Uniaxial Stress<br />

P-30 Makoto Iwata Temperature-Field Phase Diagrams in Pb(Zn 1/3Nb 2/3)O 3-8%PbTiO 3<br />

P-31 Kazuaki Taji<br />

Charge density study <strong>of</strong> BiFeO3-PbTiO 3 solid solution system with large tetragonal<br />

lattice distortion<br />

P-32 Mayuko Ogawa Electric-field-induced phase transition <strong>of</strong> BaTiO 3-based ceramics<br />

P-33 Shoichi Takeda<br />

P-34 Yuto Fujita<br />

P-35 Jae-Hyeon Ko<br />

Structural characteristics <strong>of</strong> Ca-substituted BaTiO3 in cubic phase by high energy<br />

synchrotron radiation powder diffraction<br />

Nonpolar S<strong>of</strong>t Optic Phonon <strong>of</strong> Cubic-rhombohedral Phase Transition <strong>of</strong> LaAlO3<br />

Studied by Inelastic Light Scattering<br />

Raman and Brillouin scattering studies on lead-free piezoelectric Bi0.5(Na 0.78K 0.22) 0.5xTiO3<br />

ceramics with A-site vacancies<br />

P-36 Ahmed I. Ali Electric and Dielectric Properties <strong>of</strong> reduced La 0.01Ba 0.99TiO 3<br />

P-37 Hae Jin Seog<br />

P-38 Ryo Kishimoto<br />

P-39 Masashi Igawa<br />

High piezoelectric coefficient <strong>of</strong> lead-free KNN-based thin films for MEMS<br />

application<br />

Fabrication and Characterization <strong>of</strong> Inorganic Organic Composites Using<br />

Ferroelectric Nanoplates<br />

Evaluation <strong>of</strong> switching charge density <strong>of</strong> PbTiO3 nanoislands by atomic force<br />

microscopy<br />

P-40 Dong Jin Yoon Magnetoelectric Properties <strong>of</strong> CuFe 2O 4/BaTiO 3 Bi-layer Thin Films<br />

P-41 H. J. Kim<br />

P-42 J. W. Kim<br />

P-43 R. H. Shin<br />

Electrical properties <strong>of</strong> (Bi0.9A 0.1)(Fe 0.975Cr 0.025)O 3 (A=Ho, Tb and Sm) thin films<br />

prepared by chemical solution deposition<br />

Analysis for crystal structure <strong>of</strong> rare-earth substituted BiFe0.975Zn 0.025O 3-δ thin films<br />

and their electrical properties<br />

Epitaxial growth <strong>of</strong> PbVO 3 thin films with a large tetragonality factor and their<br />

polarization reversal at nano-scale<br />

P-44 Dalhyun Do The effects <strong>of</strong> Mn contents on electrical properties <strong>of</strong> BiFeO 3<br />

P-45 Jaehong Jeong Spin waves measurement <strong>of</strong> room-temperature multiferroic BiFeO 3<br />

P-46 K. Kobayashi<br />

P-47 H. Kimura<br />

Real-space imaging <strong>of</strong> ferroelectric and structural antiphase domain walls in<br />

Hexagonal YMnO3<br />

Pressure-induced magnetic and ferroelectric phase transitions in Multiferroic<br />

EuMn2O 5<br />

P-48 Yusuke Takada Preparation <strong>of</strong> epitaxial BiFeO 3 thin films by RF planar magnetron sputtering


<strong>Poster</strong> <strong>Session</strong> II (August 9, 10:30~12:00)<br />

Number Presenter Title<br />

P-49 Chiaki Kobayashi<br />

Fabrication <strong>of</strong> PZT/ZnO core-shell nanorods with different PZT thicknesses by<br />

MOCVD<br />

P-50 Taekjib Choi Local charge conductions in multiferroic BiFeO 3 nanostructures<br />

P-51 Jong Yeog Son<br />

Intaglio Nanotemplates Based on Atomic Force Microscopy for Ferroelectric<br />

Nanodots<br />

P-52 Hikaru Igawa Terahertz time-domain spectroscopy study <strong>of</strong> LiNbO 3<br />

P-53 Akitoshi Koreeda Coherent Entropy-Wave Generation in Quantum Paraelectrics<br />

P-54 Haruki Takayama<br />

P-55 A. Yamashita<br />

Brillouin scattering study <strong>of</strong> liquid-glass transitions in ternary mixture <strong>of</strong> water,<br />

trehalose and ionic liquid<br />

Structural and dielectric investigation <strong>of</strong> the charge ordered organic compound α’-<br />

(BEDT-TTF)2IBr2<br />

P-56 Terutoshi Sakakura Orbital Order in YTiO 3 Observed by Super Accurate Synchrotron X-ray Diffraction<br />

P-57<br />

Rizwan Ahmed<br />

Malik<br />

P-58 Jin Su Park<br />

P-59 S.Y.Lim<br />

Large strain response in Nb-modified BNKT-ST lead-free piezoelectric ceramics<br />

Enhanced piezoelectric properties <strong>of</strong> lead-free (Bi0.5Na 0.5)TiO 3-BaTiO 3 thin films by<br />

pulsed laser deposition<br />

Na excess effects on dielectric and piezoelectric properties <strong>of</strong> lead free<br />

(Na0.53+xK 0.47)(Nb 0.55Ta 0.45)O 3 ceramics<br />

P-60 J. H. Choi Effect <strong>of</strong> the Porosity on Templated Grain Growth Behavior in (K,Na)NbO 3 Ceramics<br />

P-61 Amir Ullah<br />

P-62 Jong-Pil Lee<br />

P-63 Ichiro Fujii<br />

P-64 Haruka Okuda<br />

P-65 Tae Hyun Kim<br />

P-66 A. Zaman<br />

P-67 Byeong-Eog Jun<br />

P-68 C.-W. Cho<br />

Low-frequency Impedance Spectroscopy <strong>of</strong> BiAlO3 modified Bi 0.5(Na 0.75K 0.25) 0.5TiO 3<br />

lead-free piezoelectric ceramics<br />

Ferroelectric and Piezoelectric Properties <strong>of</strong> Polycrystalline PbTiO3 Film with<br />

Nanograin<br />

Piezoelectric Enhancement <strong>of</strong> Relaxor-based Lead-free Piezoelectric Ceramics by<br />

Nanodomain Engineering<br />

Piezoelectric Properties <strong>of</strong> Ternary Pb(Mn1/3Nb 2/3)O 3 PbTiO 3 PbZrO 3 System Solid<br />

Solutions<br />

Acoustic anomalies and central peaks in 0.83Pb(Mg1/3Nb 2/3)O 3–0.17PbTiO 3 single<br />

crystal studied by the micro-Brillouin scattering<br />

Influence <strong>of</strong> tantalum substitution on dielectric, ferroelectric and field-induced strain<br />

behavior <strong>of</strong> lead-free 0.99[Bi0.5(Na 0.82K 0.18) 0.5Ti1-xTax)O 3]-0.01LiSbO 3 ceramics<br />

Ferroelectric Properties <strong>of</strong> Potassium Sodium Niobium Oxides Ceramics with<br />

Tetragonal and Orthorhombic Composite Structures<br />

Composition dependence <strong>of</strong> relaxor properties <strong>of</strong> (1-x)K0.5Na 0.5NbO 3 –<br />

xBa0.5Ca 0.5TiO 3 ferroelectric ceramics<br />

P-69 Kouhei Suzuki Raman scattering study <strong>of</strong> relaxor ferroelectric Pb(Sc 1/2Nb 1/2)O 3 crystals<br />

P-70 Hiroko Yokota<br />

Domain structure observations <strong>of</strong> PMN-PT using a second harmonic generation<br />

microscope


Number Presenter Title<br />

P-71 K. Kurushima Evidence <strong>of</strong> the monoclinic phase around the MPB region in PMN-PT<br />

P-72 Shinya Tsukada<br />

Acoustic phonon behavior in (1-x)Pb(Zn1/3Nb 2/3)O 3-xPbTiO 3 relaxor ferroelectrics<br />

studied by Brillouin scattering<br />

P-73 Changhyo Hong Ferroelectric-Relaxor Composites in Bi-Based Lead-Free Ceramics<br />

P-74 Ichiro Fujii<br />

Dielectric and Piezoelectric Enhancement <strong>of</strong> New Ceramics with Artificial MPB<br />

Engineering<br />

P-75 Seongtak Yoon Electrical Properties <strong>of</strong> (Sr 0.75,La 0.25)TiO 3 Ultra-thin Films<br />

P-76 Taejun Hwang Transport Properties <strong>of</strong> Low Dimensional La 0.75Sr 0.25VO 3 Thin Films<br />

P-77 Eisuke Magome<br />

Structural study <strong>of</strong> gradient lattice distortion in BaTiO3-KNbO 3 composites with<br />

heteroepitaxial interface<br />

P-78 Myoung Pyo Chun Characterization <strong>of</strong> BN doped BaTiO 3 PTC thermister<br />

P-79 Da Jeong Kim<br />

P-80 Sang Wook Kim<br />

Grain growth and piezoelectric property <strong>of</strong> (Na 0.545K 0.47)(Nb 0.55Ta 0.45)O 3 with a<br />

sintering aid <strong>of</strong> Li 2CO 3 and MnO 2 by template grain growth method<br />

Structural analysis <strong>of</strong> lead free (Bi0.5Na 0.5)TiO 3 base ceramics using Rietveld<br />

refinement method<br />

P-81 Byeong-Eog Jun Lithium doping in the Gallium and Magnesium modified Zinc Oxides<br />

P-82 Kengo Shibata Low-Temperature Synthesis <strong>of</strong> (Na,K)NbO 3 by Dissolution-Precipitation Method<br />

P-83 Masahiko Bekki O 2 Annealing Effect on KF-Substituted BaTiO 3 Ceramics<br />

P-84 Ken Yanai<br />

P-85 Won-June Kim<br />

P-86 Hye-Jung Kim<br />

Crystal structures and polarization/piezoelectric properties <strong>of</strong> ferroelectric<br />

(Bi0.5K 0.5)TiO 3–(Bi 0.5Na 0.5)TiO 3 Single Crystals<br />

Density functional theory study <strong>of</strong> paraelectric-ferroelectric phase transition <strong>of</strong><br />

polyvinylidene difluoride<br />

First-principles study <strong>of</strong> piezoelectric and dielectric properties <strong>of</strong> a graphene-based<br />

dipolar layer<br />

P-87 Md. Noor-A-Alam Piezoelectricity and elasticity <strong>of</strong> hydrogenated boron nitride monolayer<br />

P-88<br />

Gantsooj<br />

Amarsanaa<br />

P-89 P. V. Ong<br />

Atomic displacement <strong>of</strong> Tetragonal PbTiO3 with different high electric field directions<br />

Energy-band alignment and orbital-selective charge transfer at oxygen-deficient<br />

LaAlO 3/SrTiO 3(001) interfaces<br />

P-90 Hiroki Moriwake Ferroelectric phase transition <strong>of</strong> AgNbO 3: a first-principles study


Oral Presentation<br />

(Room101, 1F, International Building)


Plenary<br />

Multiferroic vortex network with Z2×Z3 symmetry<br />

PL-1<br />

09:20 ~ 10:00, August 8<br />

S-W. Cheong<br />

Rutgers Center for Emergent Materials, Rutgers <strong>University</strong>, Piscataway, NJ 08854, USA<br />

and Laboratory for Pohang Emergent Materials, Postech, Pohang, Korea<br />

The fascinating concept <strong>of</strong> topological defects permeates ubiquitously our understanding<br />

<strong>of</strong> the early-stage universe, hurricanes, quantum matters such as superfluids and<br />

superconductors, and also technological materials such as liquid crystals and magnets. Largescale<br />

spatial configurations <strong>of</strong> these topological defects have been investigated only in a<br />

limited degree. Exceptions include the cases <strong>of</strong> supercurrent vortices or liquid crystals, but<br />

they tend to exhibit either trivial or rather-irregular configurations.<br />

Hexagonal REMnO3 (RE= rare earths) with RE=Ho-Lu, Y, and Sc, is an improper<br />

ferroelectric where the size mismatch between RE and Mn induces a trimerization-type<br />

structural phase transition, and this structural transition leads to three structural domains, each<br />

<strong>of</strong> which can support two directions <strong>of</strong> ferroelectric polarization. We reported that domains in<br />

h-REMnO3 meet in cloverleaf arrangements that cycle through all six domain configurations,<br />

Occurring in pairs, the cloverleafs can be viewed as vortices and antivortices, in which the<br />

cycle <strong>of</strong> domain configurations is reversed. Vortices and antivortices are topological defects:<br />

even in a strong electric field they won’t annihilate. These ferroelectric vortices/antivortices<br />

are found to be associated with intriguing magnetism.<br />

Recently we have found intriguing, but seemingly irregular configurations <strong>of</strong> a zoo <strong>of</strong><br />

multiferroic vortices and antivortices in h-REMnO3. These configurations can be neatly<br />

analyzed in terms <strong>of</strong> graph theory and this graph theoretical analysis reflects the nature <strong>of</strong><br />

self-organized criticality in complexity phenomena as well as the condensation and eventual<br />

annihilation processes <strong>of</strong> topological vortex-antivortex pairs. These numerous multiferroic<br />

vortices/antivortices can be understood as an arrested Kosterlitz-Thouless phase.<br />

In addition, we have discovered the emergence <strong>of</strong> Z2×Z3 symmetry in the seeminglyrandom<br />

network <strong>of</strong> numerous ferroelectric vortices, and electric poling or self-poling due to a<br />

surface charge boundary condition induces global topological condensation through breaking<br />

<strong>of</strong> the Z2 part <strong>of</strong> the Z2×Z3 symmetry. The opposite process <strong>of</strong> restoring the Z2 symmetry can<br />

be considered as topological evaporation. Our discovery opens new avenues for exploring<br />

non-trivial topology <strong>of</strong> large-scale domain configurations in complex materials, playing an<br />

essential role in macroscopic physical properties.


Plenary<br />

SHG microscope revisited<br />

Yoshiaki Uesu<br />

Department <strong>of</strong> Physics, Waseda <strong>University</strong>, Tokyo 169-8555, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : uesu93@waseda.jp<br />

PL-2<br />

13:30 ~ 14:10, August 9<br />

On the occasion <strong>of</strong> the 6th Korea-Japan Conference <strong>of</strong> Ferroelectrics in Sendai, I talked<br />

about our optical second-harmonic generation (SHG) microscope strengthening upon possible<br />

applications to ferroelectric 180°domain structure observations.[1] Since that time, exciting<br />

progress has been made in this field as a unique tool <strong>of</strong> mesoscopic structures in multiferroic<br />

crystals[2], thin films[3], and nondestructive and three-dimensional (3D) observations <strong>of</strong><br />

domain structures.[4-7]<br />

On reflecting the recent progress, following subjects are described:<br />

(1) Intrinsic issue <strong>of</strong> the visibility <strong>of</strong> 3D observations related with the momentum transfer<br />

mismatch between the fundamental and SH photons.[4]<br />

(2) Observation and characterization <strong>of</strong> periodically poled domain (PPD) structures in quasiphase<br />

matching (QPM) devices <strong>of</strong> wavelength converter with high conversion efficiency.<br />

[4-6]<br />

(3) Observations <strong>of</strong> the PPD structure in muscle fibers. Can a muscle fiber be QPM?<br />

(4) Domain structure analyses <strong>of</strong> relaxer/ferroelectric solid solutions at the morphotropic<br />

phase boundary.[7]<br />

References<br />

1. Y. Uesu, H. Yokota, S. Kawada and N. Kato, J. Korean Phys. Soc. 51, 804 (2007).<br />

2. M. Fiebig, V. V. Pavlov, and R. V. Pisarev, J. Opt. Soc. Am. B 22, 96-118 (2005).<br />

3. S. Denev, T. Lummen, E. Barnes, A. Kumar, and V. Gopalan, J. Amer. Ceram. Soc, 1-29<br />

(2011).<br />

4. J. Kaneshiro, S. Kawado, H. Yokota, Y. Uesu, and T. Fukui, J. Appl. Phys. 104, 054112<br />

(2008).<br />

5. Y. Uesu, H. Yokota, S. Kawado, J. Kaneshiro, S. Kurimura, and N. Kato, Appl. Phys. Lett.<br />

91, 182904 (2007).<br />

6. J. Kaneshiro, Y. Uesu, and T. Fukui, J. Opt. Soc. Am. B 27, 888 (2010).<br />

7. J. Kaneshiro and Y. Uesu, Phys. Rev. B 82, 184116 (2010).


Invited<br />

I- 1<br />

10:00 ~ 10:25, August 8<br />

Concurrent transition <strong>of</strong> magnetic and ferroelectric order near room<br />

temperature<br />

Chan-Ho Yang 1,2*<br />

1 Department <strong>of</strong> Physics, KAIST, Daejeon 305-701, Korea<br />

2 KAIST Institute for the NanoCentury, Daejeon 305-701, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : chyang@kaist.ac.kr<br />

In the talk, we will focus on a highly-elongated multiferroic BiFeO3 thin film, which has<br />

been newly discovered to be a quasi-layered phase stabilized through a misfit strain.[1] We<br />

will discuss underlying physics inherent in the quasi-layered structure and introduce our<br />

recent progress on the physical properties <strong>of</strong> the quasi-layered BiFeO3 films.[2] It will be<br />

presented that the magnetic Néel temperature <strong>of</strong> multiferroic BiFeO3 compound is unusually<br />

suppressed to near room temperature by heteroepitaxial misfit strain. Remarkably the<br />

ferroelectric state undergoes a first-order transition to another ferroelectric state<br />

simultaneously at the magnetic transition temperature. Our findings provide a unique example<br />

to show concurrent magnetic and ferroelectric transition at the same temperature among<br />

proper ferroelectrics. Moreover, we control the multiferroic transition by A-site substitutions.<br />

The transition temperature can be varied systematically from ~350 K to ~100 K as results <strong>of</strong><br />

chemical pressure or/and bismuth dilution effect. Finally, we will introduce our strategy to<br />

realize electrical switching <strong>of</strong> the magnetic state at room temperature based on the compounds.<br />

[1] R. J. Zeches et al., Science 326, 977-980 (2009).<br />

[2] K. T. Ko et al., Nature Communications 2, 567 (2011).


Invited<br />

I- 2<br />

11:10 ~ 11:35, August 8<br />

Two-Dimensional Oxide Nanosheets: New Solution to Nanodielectronics<br />

Minoru Osada 1,2* and Takayoshi Sasaki 1,2<br />

1 International Center for Materials Nanoarchitectnics (MANA), National Institute for<br />

Materials Science (NIMS), Tsukuba 305-0044, Japan<br />

2 CREST, JST, Kawaguchi 332-0012, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : osada.minoru@nims.go.jp<br />

The 2010 Noble prize in physics for the work on graphene emphasizes the importance <strong>of</strong><br />

new paradigm <strong>of</strong> two-dimensional (2D) crystalline materials research. Due to the excitements<br />

caused by graphene, other 2D materials have increasingly attracted fundamental research<br />

interest as they could open up unprecedented physical properties that cannot be attained in<br />

graphene. Here, we present the progress made in the properties <strong>of</strong> 2D oxide nanosheets,<br />

highlighting emerging functionalities in dielectronic applications [1, 2]. Titania- or<br />

perovskite-based nanosheets exhibit superior high-k performance (εr = 100 – 320) even at a<br />

few-nm thicknesses, which is an essential requirement for next-generation electronics [3].<br />

Additionally, nanosheet-based multilayer capacitors exceed textbook limits, opening a route<br />

to new capacitor devices. One more potentially interesting concept using 2D oxide nanosheets<br />

is designing superstructured nanohybrids such as field-effect transistors [1], spinelectronic<br />

devices [4], and artificial ferroelectric materials [5]. With these unique aspects, 2D oxide<br />

nanosheets will become an important research target in the form <strong>of</strong> “ceramic graphene” or<br />

“oxide graphene”.<br />

[1] M. Osada and T. Sasaki, J. Mater. Chem. 19, 2503 (2009) [Review].<br />

[2] M. Osada and T. Sasaki, Adv. Mater. 24, 209 (2012) [Review].<br />

[3] M. Osada et al., Adv. Mater. 18, 1223 (2006); ACS Nano 3, 1097 (2009); ACS Nano 4,<br />

4995 (2010); ACS Nano 4, 5225 (2010); Adv. Funct. Mater. 21, 3482 (2011).<br />

[4] M. Osada et al., Adv. Mater. 18, 295 (2006); PRB 73, 153301 (2006); APL 92, 253110<br />

(2008); Chem. Mater. 21, 4366 (2009); ACS Nano 5, 6871 (2011).<br />

[5] B. W. Li, M. Osada et al., ACS Nano 4, 6673 (2010); Jpn. J. Appl. Phys. 50, 09NA10<br />

(2011).


Invited<br />

I- 3<br />

11:35 ~ 12:00, August 8<br />

Two-faced periodic arrays <strong>of</strong> ZnO nanorods based on flexible grapheneplastic<br />

substrate for energy harvesting<br />

Se-Jeong Park 1 , Yoon-Hwae Hwang 1,2 and Suck Won Hong 1,2<br />

1 Dept. <strong>of</strong> Nano Fusion Technology, Pusan National. <strong>University</strong>, Miryang, 627-709, Korea<br />

2 Dept. <strong>of</strong> Nanomaterials Engineering, Pusan National. <strong>University</strong>, Miryang, 627-709, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: swhong@pusan.ac.kr<br />

Wearable and flexible energy harvesting systems could be usefully applied to various<br />

types, such as outdoor clothing, recharge for mobile devices or artificial organs, moving and<br />

bending our joints and so on. Yet, the power should approach as same value as one<br />

commercial battery to use the system in our daily life, so the most attractive point is how<br />

much we should get energy from energy harvesting system. To increase the harvesting<br />

efficiency rate, we present a simple and robust energy harvesting system <strong>of</strong> the two-faced<br />

periodic arrays <strong>of</strong> ZnO nanorods based on graphene and polyethylene terephthalate (PET)<br />

substrate via pulsed laser deposition method and low-temperature hydrothermal growth. The<br />

two-faced periodic arrays <strong>of</strong> ZnO nanorods reinforce the rate <strong>of</strong> energy harvesting whenever<br />

bending the system back and forth. Graphene-PET substrate gives excellent flexibility and the<br />

graphene sheets are inserted into the two-faced periodic arrays <strong>of</strong> ZnO nanorods and on the<br />

bottom <strong>of</strong> them due to its ideal monolayer with phi electrons. The harvesting efficiency with<br />

the two-faced system shows more enhanced than a system with the one-faced.


Invited<br />

I- 4<br />

13:30 ~ 13:55, August 8<br />

Controlled Hierarchical Nanostructures <strong>of</strong> Thin Ferroelectric Polymer<br />

Films for Non-volatile Memory Applications<br />

Cheolmin Park * , Seok Ju Kang, Youn Jung Park, Insung Bae<br />

and Richard Hahnkee Kim<br />

Department <strong>of</strong> Materials Science and Engineering, Yonsei <strong>University</strong>, Seoul 120-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : cmpark@yonsei.ac.kr<br />

Information storage devices <strong>of</strong> ferroelectric polymers such as poly(vinylidene fluoride)<br />

(PVDF) and its copolymers with trifluoroethylene (TrFE) have been <strong>of</strong> a great attention in<br />

virtue <strong>of</strong> mainly low cost solution processibility based on spin coating for their potential use<br />

in non-volatile memory technology, one <strong>of</strong> the most essential technologies in the current<br />

mobile industry. The basic ferroelectric polymer storage element is metal/ferroelectric<br />

polymer/metal (MFM) capacitor in which a ferroelectric polymer thin film sandwiched<br />

between arrays <strong>of</strong> metal electrodes that makes possible electrical charge signaling across the<br />

structure. More recently ferroelectric thin films have been applied as gate dielectric to form a<br />

Ferroelectric Field-Effect Transistor (FeFET) device structure. The polarization state <strong>of</strong> the<br />

ferroelectric gate set by the polarity <strong>of</strong> the writing gate voltage controls the electrical<br />

conductance <strong>of</strong> the channel between source and drain electrode. There have been many efforts<br />

to enhance FeFET memory performance such as nondestructive readout capability, scalability,<br />

flexibility, printing capability, endurance, and materials design including electrodes,<br />

ferroelectric and insulating layers. In this presentation, we demonstrate various novel routes to<br />

fabricate high performance nonvolatile FeFETs. For instance, using a hybrid interlayer<br />

consisting <strong>of</strong> PVDF-TrFE that is confined into nanoscopic trenches <strong>of</strong> an organosilicate (OS,<br />

dielectric), operating voltages for the devices are as low as 8 V. By confining the ferroelectric<br />

polymer into 30 nm thick OS trenches <strong>of</strong> 30 nm in width and 50 nm in periodicity, we could<br />

achieve a thin and structurally dense ferroelectric layer with crystal orientation effective for<br />

facile polarization switching. The low gate leakage <strong>of</strong> our PVDFTrFE/OS hybrid layer<br />

facilitates the fabrication <strong>of</strong> a bottom gate FeFET with a single crystalline TIPS-PEN channel<br />

that operates at such a low voltage with ON/OFF ratios larger than 10 2 , and data retention <strong>of</strong><br />

approximately 2 h under ambient conditions. Furthermore, we present a highly reliable and<br />

mechanically flexible multilevel Fe-FET with a thin PVDF-TrFE insulator. Our device is<br />

based on multileveled non-volatile drain current states <strong>of</strong> a polymeric semiconductor<br />

precisely controlled by a ferroelectric insulator. Our multilevel Fe-FET fabricated on a<br />

polymer substrate provided mechanical flexibility in which the characteristic 4-level reliable<br />

switching was also realized with more than 1,000 bending cycles at a bending radius <strong>of</strong> 5.8<br />

mm.


Invited<br />

Research Topics about solution derived PZT<br />

I- 5<br />

13:55 ~ 14:20, August 8<br />

Tatsuya Shimoda 1,2*,3<br />

1 Green Devices Research Center and 2 School <strong>of</strong> Materials Science, Japan Advanced Institute<br />

<strong>of</strong> Science and Technology, 1-1Asahidai, Nomi, Ishikawa 923-1245, Japan<br />

3 Japan Science and Technology Agency, ERATO, Shimoda Nano Liquid Process Project, 2-<br />

5-3 Asahidai, Nomi, Ishikawa 923-1211, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : tshimoda@jaist.ac.jp<br />

I will introduce research topics related solution based PZT, which have been conducted<br />

in JST-ERATO Shimoda nano-liquid process project from October 2006 to March 2012.<br />

ERATO, Exploratory Research for Advanced Technology, is one <strong>of</strong> major research funding<br />

programs provided by Japan Science and Technology Agency (JST).<br />

The research objective <strong>of</strong> ERATO Shimoda project is to create a new method to print<br />

nano-sized authentic electronics devices and circuits using functional solutions. As one <strong>of</strong> the<br />

target devices, we chose FGT (Ferroelectric Gate Transistor). As for a structure <strong>of</strong> FGT, a<br />

bottom gate one, in which ITO and PZT were a channel and gate insulator layer, respectively,<br />

was adopted. The polarization <strong>of</strong> PZT is so large that it can completely deplete the ITO<br />

channel. So, this structure can be a transistor with memory function caused by the hysteresis<br />

<strong>of</strong> PZT. Three topics will be introduced: (1) low temperature formation <strong>of</strong> PZT by using<br />

chemical solution deposition (CSD) methods, (2) totally solution processed FGT and (3) a<br />

NAND memory constructed by solution processed FGTs.<br />

(1) low temperature formation <strong>of</strong> PZT We found a novel low-temperature crystallization<br />

path where the perovskite structure were directly formed at 400 -500 degree C without<br />

passing through pyrochlore formation. This is caused by the reaction that reductive agents<br />

such as monoethanolamin or curbon reduce Pb 2+ to Pb 0 at 200-300 degree C so that there is<br />

no way for pyrochlore phase can be formed due to the shortage <strong>of</strong> Pb element.<br />

(2) totally solution processed FGT Prior to direct printing <strong>of</strong> FGT, it should be fabricated<br />

only by using solution materials . By adopting LaNiO for a gate and ITO both for a channel<br />

and source/drain electrodes, a FGT with high performance was developed. Its all layers were<br />

constructed by metal-oxide materials which were made from solution precursors.<br />

(3) NAND memory A new circuit design was invented to make a NAND circuit using<br />

FGT as a memory element. The developed NAND circuit has dual FGT cells, one <strong>of</strong> which is<br />

for a memory while the other is a pass transistor. Non-destructive writing, reading and erasing<br />

operations were demonstrated without any disturbance.


Invited<br />

I- 6<br />

14:20 ~ 14:45, August 8<br />

Tuning Ferroelectric Properties <strong>of</strong> Epitaxial Oxide Thin Films<br />

Tae Won Noh 1* , Daesu Lee 1 , Sang Mo Yang 1 , Tae Heon Kim 1 , Byung Chul Jeon 1 ,<br />

Young Jae Shin 1 and Jong-Gul Yoon 2<br />

1 ReCFI, Department <strong>of</strong> Physics and Astronomy, Seoul Nat’l Univ., Seoul 151-747, Korea<br />

2 Dept. <strong>of</strong> Physics, Univ. <strong>of</strong> Suwon, Hwaseong, Gyunggi-do 445-743, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : twnoh@snu.ac.kr<br />

Ferroelectric materials possess a spontaneous polarization that can be electrically<br />

switchable. Thus ferroelectrics have opened a possibility <strong>of</strong> electrical control <strong>of</strong> their<br />

functionality. They have been used for wide applications, such as non-volatile memory and<br />

sensor. In addition, they have shown various interesting physical properties, stimulating<br />

scientific interest by many researchers.<br />

Despite extensive studies, many aspects on ferroelectrics remain untouched. In this<br />

presentation, we will report systematic ways to tune ferroelectric properties using a couple <strong>of</strong><br />

methods: namely (1) “flexoelectricity” and (2) “displacement currents.” We will show that<br />

these approaches can enhance the application potential <strong>of</strong> ferroelectrics significantly, as well<br />

as allow their novel physical phenomena. Firstly, we will show that a giant and controllable<br />

flexoelectric effect can allow a novel opportunity to tune the physical properties <strong>of</strong><br />

ferroelectric epitaxial thin films, such as domain configurations and polarization switching<br />

behaviors [1]. Secondly, using our concept <strong>of</strong> deterministic polarization control, we will<br />

demonstrate the multilevel polarization states in real ferroelectric thin-film systems, formed<br />

by controlling displacement currents [2]. These methods illustrate the potential <strong>of</strong> controlling<br />

ferroelectric domain growth as well as scaling up the storage density <strong>of</strong> FeRAM.<br />

[1] D. Lee et al., Phys. Rev. Lett. 107, 057602 (2011)<br />

[2] D. Lee et al., Adv. Mater. 24, 402 (2012)


Invited<br />

I- 7<br />

15:15 ~ 15:40, August 8<br />

Low temperature synthesis <strong>of</strong> epitaxial and fiber-textured (K, Na)NbO3<br />

thick films grown by hydrothermal Method<br />

Hiroshi Funakubo 1* , Takahisa Shiraishi 1 , Mutsuo Ishikawa 2 and Minoru Kurosawa 1<br />

1 Interdisciplinary Graduate school <strong>of</strong> Science & Engineering, Tokyo Institute <strong>of</strong> Technology,<br />

4259-J2-43, Nagatsuta-cho, Midori-ku, Yokohama, 226-8502, Japan<br />

2 Department <strong>of</strong> Clinical Engineering Faculty <strong>of</strong> Biomedical Engineering, Toin <strong>University</strong> <strong>of</strong><br />

Yokohama, 1614 Kurogane-cho, Aoba-ku, Yokohama, 225-8503, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : funakubo@iem.titech.ac.jp<br />

Low temperature growth <strong>of</strong> functional oxide is an very important issues for the application<br />

compatible to the organic electronics. Hydrothermal method has been recognized as the potantial<br />

preparation method for growing epitaxal crystalline films even below 300 o C as well as their high<br />

growth rate. Our groups grew KNbO3 films grown at 240 o C by hydrothermal method using KOH and<br />

Nb2O5 as source materials. Film thickness increased with reaction time up to 3 h, however decreased<br />

for longer reaction times. A 16-�m-thick epitaxially grown KNbO3 films with (100)pc orientation<br />

were successfully grown on (100)cSrRuO3//(100)SrTiO3 substrates for 3 h. The relative dielectric<br />

constant and dielectric loss at 100 kHz were 415 and 8%, respectively. Clear hysteresis loops<br />

originating from ferroelectricity were observed and the remanent polarization was 20 �C/cm 2 at the<br />

maximum applied electric field <strong>of</strong> 220 kV/cm. The effective longitudinal piezoelectric constant<br />

obtained using a Laser Doppler velocimeter, was 86 pm/V. Film thickness can be extened to beyond<br />

100 �m. This process can be also used as the process to obtain bulk materials with three-<br />

dimentionally orientation control. In addition, we demostrated the preparation films <strong>of</strong> KNbO3-<br />

NaNbO3 solid solution on flexible matel foiles that is useful for the energy hervasting applications.<br />

1) M.Ishikawa et al., Mater. Res. Soc. Symp. Proc., 1139 (2009) 1139-GG03-52.<br />

2) M.Ishikawa et al., Jpn. J. Appl.Phys. , 48 (2009) 09KA14-1-4.<br />

3) M.Ishikawa et al., Jpn. J.Appl. Phys., 49 (2010) 07HF01-1-4.<br />

4) H. Einishi et al., Key Eng. Mater., 485 (2011) 199-202.<br />

5) T. Shiraishi et al., Jpn. J. Appl. Phys., 50 (2011) 09ND11-1-4.


Invited<br />

I- 8<br />

15:40 ~ 16:05, August 8<br />

Possible mechanism <strong>of</strong> giant strain in BNT-based lead-free ceramics<br />

Jae-Shin Lee 1* , Hyoung-Su Han 1 , Chang-Won Ahn 2 and Ill Won Kim 2<br />

1 School <strong>of</strong> Materials Science and Engineering, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

2 Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : jslee@ulsan.ac.kr<br />

The electric-field-induced strain (EFIS) <strong>of</strong> impurity doped (Bi,Na)TiO3-(Bi,K)TiO3<br />

(BNKT) ceramics near the morphotropic phase boundary were investigated. The dopants<br />

investigated in this work include Zr, Hf, Sn, Nb, Ta, Y, and Cu. Heterovalent dopants brought<br />

about a phase transition from coexistence <strong>of</strong> rhombohedral and tetragonal phases to a<br />

nonpolar pseudocubic phase.<br />

The impurity-induced phase transition remarkably enhanced the EFIS <strong>of</strong> BNKT<br />

ceramics even though their ferroelectric and piezoelectric properties <strong>of</strong> BNKT ceramics<br />

degraded gradually in terms <strong>of</strong> the static piezoelectric constant d33, remnant polarization,<br />

coercive field, and piezoelectric coupling coefficient. Dielectric measurements indicated that<br />

doped BNKT ceramics reveal relaxor ferroelectric (RFE) behaviors that are distinct in terms<br />

<strong>of</strong> diffuse transition points and frequency dependent peaks in dielectric permittivity.<br />

This study discusses underlying mechanisms for doping-induced strain enhancement on<br />

the basis <strong>of</strong> analyses on their microstructure, crystal structure, dielectric, and piezoelectric<br />

properties. The tolerance factor (t) <strong>of</strong> BNKT ceramics doped with various impurities was<br />

calculated and correlated with Tm (temperature at which the dielectric constant reaches<br />

maximum) and the depolarization temperature (Td). It was found that with increasing t, the Td<br />

increased while Tm decreased. On the other hand EFIS showed little relationship with the t<br />

while atomic mass <strong>of</strong> dopant seemed to have a relationship with EFIS. Many impurities such<br />

as Zr, Sn, Ta, and Nb led to a abnormal enhancement in the normalized strain Smax/Emax up to<br />

over 500 pm/V in strain-electric field (S-E) measurements. The maximum strain and Smax/Emax<br />

were 0.43% and 730 pm/V, respectively, when Nb and Li were co-doped into BNKT<br />

ceramics.<br />

In addition, such transition-induced giant strains were experimentally observed when<br />

BNKT was also modified with other ABO3-type perovskites such as LiTaO3, Sr(K,Nb)O3,<br />

BaZrO3, and CaZrO3. It is noted that the tolerance factor <strong>of</strong> other end member was found to<br />

be important for the FE-RFE phase transition. Based on our recent findings, this paper<br />

discusses the origin <strong>of</strong> the phase transition induced-giant strain in Bi-perovskites.


Invited<br />

I- 9<br />

16:05 ~ 16:30, August 8<br />

Crystallographic and Domain Structures <strong>of</strong> Ferroelectric (Li,Na)NbO3<br />

Films Fabricated by a Pulsed Laser Deposition<br />

Seiji Yamazoe*, Akihiro Kohori, Hiroyuki Sakurai and Takahiro Wada<br />

Department <strong>of</strong> Materials Chemistry, Ryukoku <strong>University</strong>, Otsu 520-2194, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : yamazoe@rins.ryukoku.ac.jp<br />

Ferroelectricity and piezoelectricity depend on crystallographic and domain structures.<br />

We have reported that the domain structure could be observed by a laser scanning microscope<br />

(LSM) [1]. A Raman spectroscopy is a powerful tool to analyze the crystal phase [2]. In the<br />

present study, we fabricated ferroelectric NaNbO3 (NN) and (LixNa(1-x))NbO3 (LNN) thin<br />

films with x = 0.05, 0.10 and 0.13 on (001)SrTiO3 (STO) substrate by a pulsed laser<br />

deposition (PLD). The crystallographic structures <strong>of</strong> the films were analyzed by X-ray<br />

diffraction and Raman spectroscopy and the domain structures were observed by LSM.<br />

NN and LNN (x = 0.05, 0.10, 0.13) films were grown on (001)STO substrate by the PLD.<br />

The SrRuO3 (SRO) bottom electrodes were deposited by the PLD before fabrication <strong>of</strong> the<br />

NN and LNN films. The crystal phases and the orientation were analyzed by X-ray diffraction<br />

and Raman spectroscopy. The domain structures were observed by LSM. The ferroelectric<br />

properties were recorded by a ferroelectric tester.<br />

The X-ray diffraction patterns show that all the films<br />

had 001 orientation. The Raman spectra clearly showed<br />

that the NN film had antiferroelectric orthorhombic phase,<br />

(Li0.05Na0.95)NbO3 (LNN05) and (Li0.10Na0.90)NbO3<br />

(LNN10) films had ferroelectric orthorhombic phase, and<br />

(Li0.13Na0.87)NbO3 (LNN13) film had a ferroelectric<br />

orthorhombic and ferroelectric rhombohedral mixed<br />

phase. The results were consistent with the observation <strong>of</strong><br />

the domain structures by LSM. We found that the crystal<br />

phase and domain structure were drastically changed by<br />

Fig. 1 LSM image <strong>of</strong> LNN13 after<br />

applying an electric field.<br />

applying an electric field. Figure 1 shows the domain structure <strong>of</strong> LNN13 after applying an<br />

electric field <strong>of</strong> 250 kV/cm. We can see that only the domain under the electrode changed.<br />

From the Raman spectra and LSM images, this drastically change is due to not only the phase<br />

transition from ferroelectric orthorhombic and rhombohedral mixed phases to rhombohedral<br />

single phase but also the change <strong>of</strong> polarization direction. We confirmed that the ferroelectric<br />

properties depend on the change <strong>of</strong> the crystal and domain structures.<br />

[1] S. Yamazoe et al., Appl. Phys. Lett., 96, 092901 (2011). [2] Y. Shiratori et al, J. Phys.<br />

Chem.C, 111, 18493 (2009).


Invited<br />

I- 10<br />

09:00 ~ 09:25, August 9<br />

Radio – Frequency Surface Acoustic and Bulk Acoustic Wave Devices with<br />

high performances and unique structures<br />

Masanori Ueda 1* , Motoaki Hara 2 , Tsuyoshi Yokoyama 1 , Takeshi Sakashita 1 ,<br />

Masafumi Iwaki 1 , Shinji Taniguchi 1 , Tokihiro Nishihara 1 , Michio Miura 1 ,<br />

Takashi Matsuda 1 and Yoshio Satoh 1<br />

1 TAIYO YUDEN CO.,LTD., 64 Nishiwaki, Okubo-cho, Akashi 674-8555, Japan<br />

2 Graduate School <strong>of</strong> Engineering, Tohoku <strong>University</strong>, 6-3 Aoba, Aramaki, Aoba-ku, Sendai<br />

980-8578, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : maueda@jty.yuden.co.jp<br />

The performances <strong>of</strong> radio-frequency (RF) surface acoustic wave (SAW) filters and<br />

duplexers have improved markedly, and they are now widely used in the mobile<br />

communication market. RF bulk acoustic resonator (BAW) filters and duplexers based on<br />

film bulk acoustic resonator (FBAR) or solidly mounted resonator (SMR) technologies are<br />

also increasingly used in the market. Requirements such as insertion losses, cut-<strong>of</strong>f<br />

performances, isolations, linearity and so on for filters and duplexers in systems are getting<br />

tighter, therefore new techniques are needed to meet specifications. In this conference, we<br />

will introduce our unique temperature compensated SAW (TC-SAW) and FBAR technologies.<br />

1. TC-SAW<br />

We have developed TC-SAW devices with hybrid substrates constructed <strong>of</strong> LiTaO3 and<br />

sapphire substrates employing a direct bonding technique at room temperature. A sapphire<br />

substrate can suppress a temperature expansion <strong>of</strong> LiTaO3 boned to a sapphire because <strong>of</strong> low<br />

temperature expansion coefficient and high young’s modulus <strong>of</strong> a sapphire, therefore a<br />

temperature drift <strong>of</strong> center frequency <strong>of</strong> a filter was improved. Thanks to good heat radiation<br />

<strong>of</strong> a sapphire, better power handling capability <strong>of</strong> a SAW duplexer was also confirmed.<br />

2. FBAR<br />

We have developed air-gap type FBARs, which are applicable not only for S-band but<br />

also for X to Ka-band frequencies. Our proposed air-gap structure is simple and cost-effective.<br />

The air-gap can be formed on the flat substrate using stress control <strong>of</strong> piezoelectric (AlN) and<br />

metal films (Ru) without using a thick sacrificial layer. Results from both simulations and<br />

experiments demonstrate that a dome-shaped air-gap was formed between the substrate<br />

surface and the bottom electrode, and that an air-gap type FBAR structure with good<br />

performance was possible. Filters and duplexer with good performances using air-gap FBARs<br />

were realized.


Invited<br />

I- 11<br />

09:25 ~ 09:50, August 9<br />

Realization <strong>of</strong> Transparent and Flexible Capacitors using Reliable<br />

Graphene Electrodes<br />

Sin-Hye Na, Hyun-A Song and Soon-Gil Yoon *<br />

Department <strong>of</strong> Materials Engineering, Chungnam National <strong>University</strong>, Daeduk Science Town,<br />

305-764 Daejeon, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : sgyoon@cnu.ac.kr<br />

Reliable graphenes grown by rapid-thermal pulse chemical vapor deposition (CVD) for<br />

electrode applications were selectively patterned under optimum conditions for argon rf<br />

plasma power and etching time. For the transparent and the flexible capacitors using<br />

Bi2Mg2/3Nb4/3O7 (BMNO) dielectric films grown at room temperature, the graphene top and<br />

bottom electrodes were integrated onto the polymer substrates. The<br />

graphene/BMNO/graphene/Ti/polyethersulfone (PES) capacitors showed typical dielectric<br />

and the leakage properties for capacitors. The adhesion between substrates and the graphene<br />

should be critically considered in order to improve the leakage properties <strong>of</strong> the capacitors.<br />

Graphene that possessed a high bendability was the predominant candidate for application to<br />

the top and bottom electrodes <strong>of</strong> the transparent and flexible capacitors.


Invited<br />

I- 12<br />

09:50 ~ 10:15, August 9<br />

Recent Progress <strong>of</strong> Ferroelectric-gate Field-Effect Transistor<br />

Based on an Oxide Heterostructure<br />

Yukihiro Kaneko 1* , Yu Nishitani 1 , Hiroyuki Tanaka 1 , Michihito Ueda 1 ,<br />

Yoshihisa Kato 2 and Eiji Fujii 1<br />

1 Advanced Technology Research Laboratories, Panasonic Corp., Kyoto 619-0237, Japan<br />

2 Semiconductor Device Development Center, Panasonic Corp., Kyoto 617-8520, Japan<br />

* E-mail address <strong>of</strong> the corresponding author: kaneko.yukihiro001@jp.panasonic.com<br />

A ferroelectric-gate field-effect transistor (FeFET), which uses ferroelectric material as a<br />

dielectric layer for a metal oxide semiconductor FET, is <strong>of</strong> great interest for nonvolatile<br />

memory devices. This is because its channel conductance can be switched and memorized<br />

continuously with low power consumption at high speed. However, it is difficult to fabricate a<br />

FeFET which has a good retention property due to the reaction between the ferroelectric and<br />

Si, when a ferroelectric is deposited directly on a Si substrate. We have focused on carrier<br />

conduction in the oxide heterostructure which can eliminate undesirable reaction layer. We<br />

chose an inverted staggered (bottom-gate) thin-film transistor structure as a novel FeFET. We<br />

fabricated a FeFET based on a combinatorial oxide structure consisting <strong>of</strong> stacked perovskite<br />

oxides with similar lattice parameters: a ferroelectric film <strong>of</strong> Pb(Zr,Ti)O3 (PZT), a bottom<br />

gate electrode <strong>of</strong> SrRuO3 (SRO), and a substrate <strong>of</strong> (100)-sliced SrTiO3 (STO). This<br />

combination enabled the heteroepitaxial growth <strong>of</strong> a PZT/SRO/STO structure with a<br />

homogeneous crystal orientation, which, in turn, led to well-oriented growth <strong>of</strong> ZnO on top <strong>of</strong><br />

the PZT. This gave rise to a very sharp ZnO/PZT interface. The fabricated FeFET showed<br />

electron gas accumulation and complete depletion switching due to the ferroelectric<br />

polarization reversal. As a result, it showed not only the continuous conductance modulation<br />

with wide range but also a very long retention time that exceeded 3.5 months [1,2]. We can<br />

predict a ten-year data retention in a FeFET. In addition, we revealed that the channel<br />

formation originated from the ferroelectric domain wall movement from the channel edge to<br />

the center [3]. We also succeeded the fabrication <strong>of</strong> a FeFET on a Si-substrate, <strong>of</strong> which<br />

electrical property was as same as that on STO [4]. These characteristics are suitable for not<br />

only nonvolatile memory, which consists <strong>of</strong> NOR- and NAND-type FeFET memory cells<br />

[2,5], but also analog memory applications, such as neural networks [6].<br />

[1] Y. Kato, et. al., Jpn. J. Appl. Phys. 47 (2008) 2719. [2] Y. Kaneko, et. al., IEEE Trans. Electron Devices 58<br />

(2011) 1311. [3] Y. Kaneko, et. al., J. Appl. Phys. 110 (2011) 084106 [4] H. Tanaka, et. al., Jpn. J. Appl. Phys.<br />

47 (2008) 7527. [5] Y. Kaneko, et. al., Jpn. J. Appl. Phys. 48 (2009) 09KA19. [6] M. Ueda, et. al., J. Appl. Phys.<br />

110 (2011) 086104.


Invited<br />

I- 13<br />

14:10 ~ 14:35, August 9<br />

Ferroelectricity and magnetoelectric coupling in superlattices composed <strong>of</strong><br />

non-ferroic components<br />

Ji Won Seo 1* and Jaichan Lee 1<br />

1 School <strong>of</strong> Advanced Materials Science and Engineering, Sungkyunkwan <strong>University</strong>,<br />

Suwon 440-746, Republic <strong>of</strong> Korea<br />

* E-mail address <strong>of</strong> the corresponding author : jiwonseo606@gmail.com<br />

Phase transitions during crystal symmetry changes in ferroic materials are well known to<br />

give rise to their electrical and magnetic properties. Conversely, materials devoid <strong>of</strong> ferroics<br />

are presumed not to display any macroscopic type <strong>of</strong> ordering such as ferroelectricity or<br />

ferromagnetism. Recently however, oxide-based heterostructures have exposed a wealth <strong>of</strong><br />

phenomena at the boundaries where compounds with different electronic properties meet,<br />

giving unprecedented access to novel properties. Examples include novel metallic, magnetic<br />

and superconducting characteristics in multilayers composed <strong>of</strong> non-magnetic insulators.<br />

Here, we report the discovery <strong>of</strong> ferroelectricity and strong magnetoelectric coupling in threecomponent<br />

superlattices consisting <strong>of</strong> solely non-ferroelectric and anti-ferromagnetic<br />

NdMnO3/SrMnO3/LaMnO3 layers. Ferroelectricity plateau was observed below 40 K and<br />

magnetoelectric coupling was found to result in close to a 200% magnetic modulation <strong>of</strong> the<br />

electrical polarization. Our results demonstrate a fascinating example <strong>of</strong> the emergence <strong>of</strong><br />

unprecedented physical properties in artificially grown correlated electron oxides structures.


Invited<br />

I- 14<br />

14:35 ~ 15:00, August 9<br />

In-Situ X-Ray Nanodiffraction <strong>of</strong> Ferroelectric Heterostructures<br />

Ji Young Jo 1* , Pice Chen 2 , Rebecca J. Sichel 2 , Eric M. Dufresne 3 , Matthew Dawber 4 ,<br />

Ho Nyung Lee 5 , Serge M. Nakhmanson 6 and Paul G. Evans 2<br />

1 School <strong>of</strong> Materials Science and Technology, GIST<br />

2 Department <strong>of</strong> Materials Science and Technology, <strong>University</strong> <strong>of</strong> Wisconsin-Madison<br />

3 Advanced Photon Source, Argonne National Laboratory<br />

4 Department <strong>of</strong> Physics, Stony Brook <strong>University</strong><br />

5 Materials Science and Technology Division, Oak Ridge National Laboratory<br />

6 Materials Science Division, Argonne National Laboratory<br />

* E-mail address <strong>of</strong> the corresponding author: jyjo@gist.ac.kr<br />

The responses <strong>of</strong> ferroelectric heterostructures to external electric fields provide<br />

functionalities including electromechanical distortion and switching <strong>of</strong> remnant polarization<br />

at nanometer scale. Nano-scaled features <strong>of</strong> ferroelectric heterostructures such as components<br />

<strong>of</strong> ferroelectric/dielectric superlattices with nanometer-scale repeating units and ferroelectric<br />

domains have been predicted to possess novel electromechanical properties. However,<br />

electromechanical properties <strong>of</strong> nano-scaled features have not previously been probed<br />

individually due to a lack <strong>of</strong> in-situ imaging methods. To study the electromechanical<br />

responses arising from the ferroelectric and/or dielectric components, we have performed a<br />

synchrotron X-ray microdiffraction study <strong>of</strong> a BaTiO3-CaTiO3 and PbTiO3-SrTiO3<br />

superlattices. In our electrimechanical studies, we found intriguing results: (1) both<br />

ferroelectric and dielectric components contribute equally to the overall piezoelectric strain, 1<br />

(2) The time required to reach the maximum strain decreases with increase <strong>of</strong> the magnitude<br />

<strong>of</strong> the applied electric field due to the switching <strong>of</strong> nano-stripe domains, 2 and (3) domains<br />

written by piezoresponse force microscopy exhibit the strain up to 0.1%. 3 In this presentation,<br />

we will discuss details <strong>of</strong> our recent results.<br />

1 J.Y. Jo et al., Phys. Rev Lett. 104, 207601 (2010)<br />

2 J.Y. Jo et al., Phys. Rev Lett. 107, 055501 (2011)<br />

3 J.Y. Jo et al., Nano Lett. 11, 3080 (2011)


Invited<br />

I- 15<br />

09:00 ~ 09:25, August 10<br />

Effect <strong>of</strong> Ca-Substitution on the Ferroelectricity in CdTiO3<br />

Hiroki Taniguchi 1* , Hiroki Moriwake 2 and Mitsuru Itoh 1<br />

1 Materials and Structures Laboratory, Tokyo Inst. <strong>of</strong> Technology, Yokohama 226-8503,<br />

Japan<br />

2 Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan<br />

* E-mail address <strong>of</strong> the corresponding author: taniguchi.h.aa@m.titech.ac.jp<br />

Many studies have been devoted to clarify an origin <strong>of</strong> ferroelectricity in perovskite-type<br />

oxides to date. A series <strong>of</strong> recent studies suggested that covalency plays a crucial role in an<br />

appearance <strong>of</strong> the ferroelectricity.[1] An octahedral rotation is also known as a key factor in<br />

the ferroelectric phase transition in the perovskite-type oxides. It is, however, not clear how<br />

the covalency works under the existence <strong>of</strong> octahedral rotations. In the present study, we have<br />

investigated the role <strong>of</strong> covalency in the ferroelectricity <strong>of</strong> perovskite-type oxides with preexisting<br />

octahedral rotations, by examining Ca-substitution effect on the ferroelectricity <strong>of</strong><br />

CdTiO3.<br />

CdTiO3 has an orthorhombic Pnma structure at room temperature with (a + b - b - )-type<br />

octahedral rotations in the Glazer's notation, undergoing the phase transition into a<br />

ferroelectric Pna21 phase at Tc ~ 85 K.[2] The phase transition is triggered by s<strong>of</strong>tening <strong>of</strong> a<br />

ferroelectric s<strong>of</strong>t mode, indicating a so-called displacive-type ferroelectric phase transition.[3]<br />

In contrast, CaTiO3 that is an isomorph <strong>of</strong> CdTiO3 is paraelectric down to 0 K, in spite <strong>of</strong> its<br />

similar crystal structure with CdTiO3. The marked difference between their phase transition<br />

properties is expected to stem from different covalency <strong>of</strong> A-site ions, where<br />

electronegativities <strong>of</strong> Cd and Ca are 1.7 and 1.0, respectively, whereas that <strong>of</strong> O is 3.5.<br />

Raman scattering experiments are performed in the present study on (Cd1-xCax)TiO3 (x =<br />

0 - 0.05) as functions <strong>of</strong> Ca-concentration and temperature. The s<strong>of</strong>tening <strong>of</strong> the s<strong>of</strong>t mode is<br />

found to be suppressed by the Ca-substitution to decrease Tc. First-principles calculations<br />

clarify the s<strong>of</strong>t mode in CdTiO3 is dominated by O-Cd-O asymmetric stretching, which is<br />

closely related to the Cd-O covalent bond along the direction <strong>of</strong> spontaneous polarization in<br />

the ferroelectric phase. It is finally suggested that weakening <strong>of</strong> the A-site covalency due to<br />

the Ca-substitution causes the suppression <strong>of</strong> s<strong>of</strong>t-mode-s<strong>of</strong>tening, leading to the lowering <strong>of</strong><br />

Tc. The present result indicates the A-site covalency also plays an important role in the<br />

ferroelectricity in perovskite-type oxides with the pre-existing octahedral rotations.[4]<br />

References:<br />

[1] R. E. Cohen, NATURE 358, 136 (1992), Y. Kuroiwa et al., Phys. Rev. Lett. 87, 217601<br />

(2001). [2] Y. J. Shan et al., Ferroelectrics 270, 381 (2002), H. Moriwake et al., Phys. Rev. B<br />

84, 104114 (2011). [3] H. Taniguchi et al., Phys. Rev. B 76, 212103 (2007). [4] H. Taniguchi<br />

et al., Phys. Rev. B 84, 174106 (2011)


Invited<br />

I- 16<br />

09:25 ~ 09:50, August 10<br />

Phase transition behaviors <strong>of</strong> PbZr1-xTixO3 single crystals as revealed<br />

by elastic anomalies and central peaks<br />

Jae-Hyeon Ko 1* , Tae Hyun Kim 1,2 , Seiji Kojima 2 , Alexei A. Bokov 3 , Xifa Long 3<br />

and Zuo-Guang Ye 3<br />

1 Department <strong>of</strong> Physics, Hallym <strong>University</strong>, Gangwondo 200-702, Korea<br />

2 Graduate School <strong>of</strong> Pure and Applied Sciences, Univ. <strong>of</strong> Tsukuba, Ibaraki 305-8573, Japan<br />

3 Department <strong>of</strong> Chemistry and 4D LABS, Simon Fraser Univ., BC V5A 1S6, Canada<br />

* E-mail address <strong>of</strong> the corresponding author : hwangko@hallym.ac.kr<br />

Two PbZr1-xTixO3 (PZT) single crystals with x ≈ 0.45<br />

(PZT-45) and 0.42 (PZT-42) near the morphotropic phase<br />

boundary (MPB) were studied by Brillouin light<br />

scattering, giving rise to the first single-crystal elastic data<br />

which were discussed in terms <strong>of</strong> the correlation between<br />

the acoustic anomalies and the phase transition sequence.<br />

It is found that successive phase transitions <strong>of</strong> PZT single<br />

crystals accompanied significant elastic anomalies and<br />

were sensitive to the Ti concentration, which reveals new<br />

insights into the nature <strong>of</strong> phase transitions and phase<br />

diagram <strong>of</strong> PZT. The intense excitation <strong>of</strong> the central peak<br />

(CP) in the paraelectric phase suggested the formation and<br />

growth <strong>of</strong> polarization fluctuations. The relaxation time<br />

estimated from the CP width increased upon cooling<br />

toward TC, indicating a slowing-down <strong>of</strong> precursor dynamics. The thermal hysteresis in the<br />

ferroelectric phase transition indicated a first-order character <strong>of</strong> the ferroelectric phase<br />

transition for PZT-42 and an almost second-order character for PZT-45, suggesting that there<br />

might be a tricritical point between these two compositions. A diffuse elastic s<strong>of</strong>tening and a<br />

hypersonic damping were observed in both PZT single crystals below room temperature, from<br />

which the phase boundary <strong>of</strong> the antiphase tilting transition <strong>of</strong> oxygen octahedra was<br />

determined accurately.<br />

* This research was supported by Basic Science Research Program through the National<br />

Research Foundation <strong>of</strong> Korea (NRF) funded by the Ministry <strong>of</strong> Education, Science and<br />

Technology (2010-0010497), by the U.S. Office <strong>of</strong> Naval Research (N00014-06-10166;<br />

N00014-11-1-0552), and by the Natural Science and Engineering Research Council <strong>of</strong><br />

Canada (NSERC).


Invited<br />

I- 17<br />

09:50 ~ 10:15, August 10<br />

Study <strong>of</strong> local structural fluctuations in ferroelectric BaTiO3<br />

using convergent-beam electron diffraction<br />

Kenji Tsuda 1* , Rikiya Sano 1 and Michiyoshi Tanaka 1<br />

1 Institute <strong>of</strong> Multidisciplinary Research for Advanced Materials, Tohoku <strong>University</strong>,<br />

Sendai 980-8577, Japan<br />

* E-mail address <strong>of</strong> the corresponding author: k_tsuda@tagen.tohoku.ac.jp<br />

Convergent-beam electron diffraction (CBED) is established as the most powerful<br />

technique to determine crystal point- and space-groups from nanometer-sized specimen areas.<br />

The CBED method was extended to quantitative crystal structure analysis by Tsuda and<br />

Tanaka [1, 2], which enables determinations <strong>of</strong> structural parameters such as atom positions,<br />

atomic displacement parameters (ADPs), as well as electrostatic potential and electron density<br />

distributions. Recently, the method was successfully applied to the electrostatic potential<br />

analyses <strong>of</strong> silicon [3] and the orbital ordered phase <strong>of</strong> spinel oxide FeCr2O4 [4].<br />

The CBED method has been applied to ferroelectric phases <strong>of</strong> perovskite-type BaTiO3 in<br />

the present study. It is well known that BaTiO3 undergoes successive phase transformations<br />

from the cubic paraelectric phase to three ferroelectric phases: tetragonal, orthorhombic and<br />

rhombohedral ones. The mechanism <strong>of</strong> the phase transformations is, however, still not<br />

sufficiently understood. It was pointed out from theoretical calculations that BaTiO3 is not<br />

described as a simple displacive model but has some degree <strong>of</strong> order-disorder character [5].<br />

Energy-filtered CBED patterns <strong>of</strong> the tetragonal, orthorhombic and rhombohedral phases<br />

were obtained from nanometer-sized specimen areas using a JEM-2010FEF energy-filter<br />

transmission electron microscope operated at an accelerating voltage <strong>of</strong> 100 kV with a liquidnitrogen<br />

cooling specimen holder.<br />

In the tetragonal and orthorhombic phases, CBED patterns were found to <strong>of</strong>ten show<br />

lower symmetries than those expected from their phases. In contrast, no symmetry breaking<br />

<strong>of</strong> CBED patterns was observed in the rhombohedral phase. These indicate that the tetragonal<br />

and orthorhombic phases essentially have characteristic local structural disorders related to<br />

their phase transformations, but the rhombohedral phase has no such disorder. From the<br />

patterns <strong>of</strong> the rhombohedral phase, atom positions, anisotropic ADPs and some low-order<br />

structure factors were successfully refined and the electrostatic potential and electron<br />

distribution were reconstructed.<br />

References: [1] K. Tsuda and M. Tanaka, Acta Cryst. A55, 939 (1999). [2] K. Tsuda, et al., Acta<br />

Cryst. A58, 514 (2002). [3] Y. Ogata, K. Tsuda and M. Tanaka, Acta. Cryst. A64, 587 (2008). [4] K.<br />

Tsuda, et al., Phys. Rev. B81, 180102 (2010). [5] W. Zhong, D. Vanderbilt and K. M. Rabe, Phys. Rev.<br />

Lett. 73, 1861 (1994).


Invited<br />

I- 18<br />

10:15 ~ 10:40, August 10<br />

Domain response by electric fields in PMN-PT: An In-situ transmission<br />

electron microscopy study<br />

Yukio Sato 1,2* , Tsukasa Hirayama 2 and Yuichi Ikuhara 1,2<br />

1 Institute <strong>of</strong> Engineering Innovation, <strong>University</strong> <strong>of</strong> Tokyo, Tokyo 113-8656, Japan<br />

2 Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : y_sato@sigma.t.u-tokyo.ac.jp<br />

Single crystal <strong>of</strong> PMN-PT (Pb(Mg1/3Nb2/3)O3-PbTiO3) is known to show high<br />

piezoelectricity, when the composition is close to the morphotropic phase boundary region.<br />

For better understanding <strong>of</strong> the high-piezoelectricity mechanism, not only the crystal structure,<br />

which have been intensively investigated, but also the domain structure should be well<br />

understood. Although there have been some reports on static domain structure <strong>of</strong> PMN-PT<br />

with MPB composition, reports on domain responses to external stimuli such as electric fields<br />

are quite limited. Here, we introduce our recent studies on real-time visualization <strong>of</strong> domain<br />

responses with the use <strong>of</strong> in-situ transmission electron microscopy [1,2].<br />

Domain structure <strong>of</strong> PMN-PT miniaturizes down to nano-meter scale, when the<br />

composition is close to MPB (Fig. (a)). We find, for poled crystal, that domains quickly<br />

respond upon electrical biasing that exceeds a certain critical value. Nanodomains and domain<br />

walls (DWs) reorient upon the biasing without largely changing the density and, on the other<br />

hand, number <strong>of</strong> micro-scale DWs reduces, showing the tendency to be more like singledomain<br />

state. The response is reversible; the domain structure comes back to the original state<br />

upon the release <strong>of</strong> the electric field. Further details will be given in our talk.<br />

Figure. TEM images (a) before biasing and (b) under biasing the electric field <strong>of</strong> ~ 24.4 kV<br />

along [111]. Corresponding domain structures are shown in (c) and (d).<br />

References:<br />

[1] Y. Sato et al., Phys. Rev. Lett., 107, 187601-1-5 (2011).<br />

[2] Y. Sato et al., Appl. Phys. Lett., 100, 172902-1-3 (2012).


Invited<br />

I- 19<br />

10:55 ~ 11:20, August 10<br />

Resistive switching characteristics <strong>of</strong> metal-oxide nanoparticle assembly<br />

Tae-Sik Yoon 1*<br />

1 Department <strong>of</strong> Materials Science and Engineering, Myongji <strong>University</strong>, Yongin,<br />

Gyeonggi-do 449-728, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : tsyoon@mju.ac.kr<br />

The resistive switching characteristics <strong>of</strong> metal-oxide nanoparticle (NP) assembly will be<br />

discussed for various resistive switching-based devices such as nonvolatile resistive random<br />

access memory (ReRAM), memristor, atomic switch, and so on. In particular, the NPs were<br />

utilized as switching elements in contrast to the conventional thin films. Since the resistive<br />

switching associates the nanoscale changes in metal-oxide layer including local phase change<br />

between insulating and conducting phases, redistribution <strong>of</strong> vacancies or impurities, redox<br />

reaction, etc, it is highly required to control these nanoscale phenomena to achieve the<br />

uniform and reliable switching characteristics. Besides the application to current Si-based<br />

electronics, it is also necessary to develop the proper methods for the flexible device<br />

fabrication such as solution-based and low temperature processes. Considering these<br />

requirements, the use <strong>of</strong> colloidal NPs is expected to be viable route due to following<br />

advantages. The colloidal NPs are prepared as dispersed in solution and can be self-assembled<br />

to be uniform layer upon drying the solvent through low-temperature solution processes. Also,<br />

the nanoscale tuning <strong>of</strong> NPs such as doping with impurities, forming core-shell structure,<br />

shaping NPs with various forms, and so on, is possible to control the resistive switching<br />

characteristics. In this presentation, the synthesis, self-assembly, and resistive switching<br />

characteristics <strong>of</strong> metal-oxide nanoparticles such as Fe2O3, NiO, BaTiO3 as well as Pt-Fe2O3<br />

core-shell nanoparticles will be discussed.


Invited<br />

I- 20<br />

11:20 ~ 11:45, August 10<br />

Enhanced ferroelectric properties <strong>of</strong> bismuth layer-structured ferroelectric<br />

thick films obtained by aerosol deposition method<br />

Muneyasu Suzuki* and Jun Akedo<br />

Advanced Manufacturing Research Institute, National Institute <strong>of</strong> Advanced Industrial<br />

Science and Technology, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : Suzuki.muneyasu@aist.go.jp<br />

Bismuth layer-structured ferroelectrics has been regarded as a promising material for<br />

applications involving ferroelectric memories and piezoelectric devices operating at high<br />

temperatures due to its large spontaneous polarization (Ps) and high Curie temperature. Since<br />

the layered structure leads to a strong anisotropy <strong>of</strong> the functional properties, it is <strong>of</strong> great<br />

interest to control crystallographic orientation <strong>of</strong> grains in the form <strong>of</strong> polycrystalline<br />

ceramics and films for achieving superior properties. The Aerosol Deposition (AD) method,<br />

which is based on room temperature impact consolidation (RTIC) phenomena, is attracting<br />

attention because it can form thick ceramic layers <strong>of</strong> simple or complex compositions at a<br />

room temperature. In this study, SrBi2Ta2O9 (SBTa), Bi4Ti3O12 (BiT) and SrBi4Ti4O15 (SBTi)<br />

ceramic thick films on glass and Pt/Ti/YSZ substrates were prepared by the AD method, and<br />

their microstructure and polarization properties were investigated. Scanning electron<br />

microscopy (SEM) observation revealed that starting powder <strong>of</strong> SBTa prepared by a solid<br />

state reaction had spherically-shaped particles with the size <strong>of</strong> 1−3 �m, and starting powder <strong>of</strong><br />

BiT prepared by a fused salt synthesis had plate-like shaped particles with the size <strong>of</strong><br />

approximately 1 μm. Additionally, BiT starting powder prepared by a solid state reaction<br />

represented square-like particles. XRD patterns measured on the surface <strong>of</strong> SBTa thick films<br />

obtained by the AD method indicated random orientation. Compared with the BiT thick films<br />

on glass substrates deposited using the starting powder (solid state reaction), the BiT thick<br />

films prepared using BiT starting powder (fused salt synthesis) exhibited a much high<br />

intensity ratio <strong>of</strong> 001 to 118. The BiT thick films on Pt/Ti/YSZ substrates were annealed at<br />

700 °C for 30min. The annealed BiT thick films represented a remanent polarization (Pr) <strong>of</strong><br />

14 μC/cm 2 and a coercive field (Ec) <strong>of</strong> 70 kV/cm, which are larger than those <strong>of</strong> sintered bulk<br />

(Pr = 9.3 μC/cm 2 and Ec = 33 kV/cm).


Contributed<br />

Charge ordering phenomena in YFe2O4<br />

C- 1<br />

10:25 ~ 10:40, August 8<br />

S. Mori 1.* , Y. Horibe 2 , T. Nagata 3 and N. Ikeda 3<br />

1 Department <strong>of</strong> Materials Science, Osaka Prefecture <strong>University</strong>, Sakai, 599-8531, Japan.<br />

2 Department <strong>of</strong> Physics and Astronomy, Rutgers <strong>University</strong>, Piscataway, NJ, 08854, USA<br />

3 Department <strong>of</strong> Physics, Okayama <strong>University</strong>, Okayama 700-8530, Japan.<br />

* E-mail address <strong>of</strong> the corresponding author : mori@mtr.osakafu-u.ac.jp<br />

Mixed-valence ferrites RFe2O4-δ (R=Y, Yb, and Lu) are one <strong>of</strong> the multiferroic materials<br />

which is well-known for the presence <strong>of</strong> charge ordering (CO) <strong>of</strong> Fe 2+ and Fe 3+ ions on<br />

geometrically frustrated triangular lattices[1]. RFe2O4-δ has the rhombohedral crystal structure<br />

(space group: R 3 m) characterized by the alternative stacking <strong>of</strong> triangular-lattice Fe-O<br />

bilayers and R-O layers along the [001] direction, and exhibits strong two-dimensionality.<br />

Charge imbalance within bilayers in the CO state <strong>of</strong> LuFe2O4 is suggested to be responsible<br />

for ferroelectricity below the two dimensional (2D) three-fold CO transition temperature at<br />

about 350 K. This CO-driven ferroelectricity can be a new mechanism for ferroelectricity<br />

from the degree <strong>of</strong> freedom <strong>of</strong> spin and charge. The evolution <strong>of</strong> three-fold CO from 2D to<br />

three dimensional (3D) in the geometrically frustrated lattice leads to a structural phase<br />

transition with a development <strong>of</strong> double periodicity along the [001]* direction in LuFe2O4-δ<br />

and YFe2O4-δ. In this work, the low-temperature superstructure <strong>of</strong> YFe2O4-δ was carefully<br />

investigated by transmission electron microscopy (TEM). We found that the unique<br />

superstructure at about 100 K is characterized by 1/14 2 / 7 1/14 -type superlattice reflection<br />

spots, suggesting the presence <strong>of</strong> charge reordering process [2]. The low-temperature highresolution<br />

images clearly show superlattice modulations in Y-O layers as well as Fe-O layers.<br />

The modification <strong>of</strong> intra-bilayer charge interactions due to lattice distortions in Y-O layers is<br />

discussed to play a crucial role in the stabilization <strong>of</strong> long-periodic superstructures at low<br />

temperatures. We will also report our experimental results on charge ordering phenomena in<br />

single crystals <strong>of</strong> RFe2O4-δ (R=Y, Yb, Lu) [3].<br />

References<br />

[1] Y. Yamada et al., J. Phys. Soc. Jpn. 66, 3733 (1997). Phys. Rev. B 62, 12167 (2000).<br />

N. Ikeda et al., Nature (London) 436, 1136 (2005).<br />

[2] Y.Horibe, N. Ikeda, K. Yoshii, and S. Mori, Phys. Rev. B82, 184119 (2010).<br />

[3].K. Matsumoto, et al., J. Phys. Conference Series, 320, 012085 (2011).<br />

Y. Matsuo, et al., J. Phys. Conference Series, 200, 012128 1-4 (2010).<br />

Y. Horibe, et al., Phys. Rev. B80, 092104 (2009).


Contributed<br />

C- 2<br />

10:40 ~ 10:55, August 8<br />

Ferroelectric polarization driven by divalent ion-substitution into epitaxial<br />

gallium iron oxide thin films<br />

R. H. Shin 1,2 , S. H. Oh 1 , W. Jo 1* , C. Lefevre 3 , C. Meny 3 and N. Viart 3<br />

1 Department <strong>of</strong> Physics, Ewha Womans <strong>University</strong>, Seoul, Korea<br />

2 CNRS-EWHA International Research Center, Ewha Womans <strong>University</strong>, Seoul, Korea<br />

3 Institute <strong>of</strong> Physics and Chemistry <strong>of</strong> Materials <strong>of</strong> Strasbourg, UMR 7504 <strong>University</strong> <strong>of</strong><br />

Strasbourg-CNRS, Strasbourg, 67043, France<br />

* E-mail address <strong>of</strong> the corresponding author : wmjo@ewha.ac.kr<br />

Recently, D. Stoeffler reported a first-principles study <strong>of</strong> the electric polarization and <strong>of</strong><br />

its switching in the multiferroic GaFeO3 system [1]. However, experimental evidence <strong>of</strong><br />

ferroelectric switching in this material has not been observed yet due to its mobile charges<br />

vulnerable to external electrical bias. A specific composition like Ga0.6Fe1.4O3 (GFO) has<br />

been extensively studied by our group over the last few years [2]. Epitaxial and<br />

polycrystalline thin-films <strong>of</strong> GFO on various substrates are elaborated but macroscopic<br />

polarization reversal in the films shows little saturation even up to 500 kV/cm. The GFO<br />

thin films, where electrons between Fe 2+ and Fe 3+ sites are itinerant, shows large DC<br />

conductivity. In order to reduce the current transport in the films, divalent ion-substitution<br />

<strong>of</strong> Mg 2+ and Co 2+ is attempted. By controlling concentration <strong>of</strong> the substituted ions, the<br />

current density <strong>of</strong> the ion-substituted GFO thin films was surprisingly reduced by 10 3 or<br />

larger. Ferroelectric polarization <strong>of</strong> the ion-substituted GFO thin films was measured using<br />

macroscopic switching measurement and piezoresponse force microscopy. At the<br />

composition that exhibit lowest conductivity, we obtain a promising polarization reversal<br />

behaviors with significant remnant polarization and domain wall switching.<br />

[1] D. Stoeffler, J. Phys.: Condens. Matter 24, 185502 (2012).<br />

[2] M. Trassin et al. Appl. Phys. Lett. 91, 202504 (2007); J. Mater. Chem.19, 8876 (2009).


Contributed<br />

C- 3<br />

12:00 ~ 12:15, August 8<br />

Capabilities <strong>of</strong> BaTiO3 and SrTiO3 Nanocube Self-Assemblies<br />

Kazumi Kato 1 , Ken-ichi Mimura 1 , Feng Dang 1,2 , Hiroaki Imai 2 , Satoshi Wada 3 ,<br />

Hajime Haneda 4 and Makoto Kuwabara 5<br />

1 National Institute <strong>of</strong> Advanced Industrial Science and Technology, 2266-98 Anagahora,<br />

Shimoshidami, Moriyama, Nagoya, Japan<br />

2 Keio <strong>University</strong>, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Japan<br />

3 <strong>University</strong> <strong>of</strong> Yamanashi, 4-3-11, Takeda, K<strong>of</strong>u, Japan<br />

4 National Institute for Materials Science, 1-1 Namiki, Tukuba, Japan<br />

5 Kyushu <strong>University</strong>, 6-1 Kasuga-kouen Kasuga, Fukuoka, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : kzm.kato@aist.go.jp<br />

The BaTiO3 and SrTiO3 nanocubes were synthesized by hydrothermal method using a<br />

water-soluble titanium complex. The microstructure <strong>of</strong> dielectric nanocubes was observed<br />

by a high resolution transmission electron microscope (HR-TEM). The size <strong>of</strong> BaTiO3 and<br />

SrTiO3 nanocubes was about 15 nm. The high magnification pr<strong>of</strong>iles indicated that each had<br />

a cubic shape with sharp edges and clear lattice fringes without inner voids. Based on these<br />

crystallographic appearances, the nanocubes were confirmed to be high quality single crystals.<br />

The capillary force assisted self-assembly method was adopted to fabricate the ordered<br />

structures on Si and Pt-coated Si substrates. The orderly region <strong>of</strong> BaTiO3 nanocubes was<br />

over a very wide range in tens <strong>of</strong> micrometers because <strong>of</strong> the narrow size and shape<br />

distributions <strong>of</strong> nanocubes in non-polar organic solvent. BaTiO3 nanocubes were assembled<br />

face to face and the resultant structure <strong>of</strong> assembly was dense in order. The relative density<br />

<strong>of</strong> the assemblies was about 98%. The piezoelectric properties <strong>of</strong> the orderly assemblies on<br />

Pt-coated Si substrate were characterized by a piezoresponse force microscope (PFM). The<br />

SrTiO3 nanocubes assemblies showed a linear d33-V relation because <strong>of</strong> the paraelectric<br />

electrostriction. On the other hand, the BaTiO3 nanocubes assemblies exhibited a<br />

ferroelectric hysteresis loop. The mixture nanocube assemblies showed a distinguished<br />

behavior, which was a combination <strong>of</strong> non-linear in the range <strong>of</strong> low poling field and stepwise<br />

changes in the range <strong>of</strong> high poling field. It suggested that BaTiO3/SrTiO3 hetero-interfaces<br />

were existed in the assembly <strong>of</strong> mixture nanocubes and affected the dielectric properties.<br />

The interface-designed structures consisted <strong>of</strong> cubic shaped dielectric building blocks have<br />

potentials to tune the piezoresponse properties and would be expected for future dielectric<br />

device applications. Great capabilities <strong>of</strong> the dielectric nanocubes will be addressed.<br />

This work was supported by the Collaborative Research Consortium <strong>of</strong> Nanocrystal<br />

Ceramics in Japan.


Contributed<br />

C- 4<br />

14:45 ~ 15:00, August 8<br />

Examination on the ferroelectricity in HfxZr1-xO2 thin film<br />

Min Hyuk Park * , Han Joon Kim, Yu Jin Kim, Hyo Kyeom Kim, Il-Hyuk Yoo<br />

and Cheol Seong Hwang<br />

WCU Hybrid Materials Program, Department <strong>of</strong> Material Science & Engineering and Interuniversity<br />

Semiconductor Research Center, Seoul National <strong>University</strong>, Seoul 151-744, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : pmh1983@snu.ac.kr<br />

Ferroelectric (FE) thin fims have been considered as the most feasible material for<br />

universal random access memory thanks to their bistable polarization which can be fast and<br />

reversibly switched by a small voltage pulses. However, the development <strong>of</strong> ferroelectric<br />

memories, such as FeRAM and FeFET, has been deterred mainly due to the difficulty <strong>of</strong><br />

fabricating nano meter scale ferroelectric thin films which usually have complicated chemical<br />

composition and crystal structures. Most extensively studied FE materials are PZT and SBT,<br />

but they are still not in large scale volume production due to many issues, such as too thick<br />

minimum thickness to be used in 20 – 30 nm scale memory devices and difficult fabrication<br />

<strong>of</strong> them on three dimensional (3D) geometry. Recently, ferroelectricity in HfO2-based<br />

materials with various dopants was reported, which could be a new pathway for the giga-bit<br />

density FE memories due to the following reasons. First, HfO2 is compatible with<br />

conventional Si technology, and it is already used in mass production. Second, relatively thin<br />

(


Contributed<br />

C- 5<br />

16:30 ~ 16:45, August 8<br />

Sintering <strong>of</strong> (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead – free piezoelectric ceramics.<br />

John G. Fisher 1* , Dae-Gi Lee 1 , Jeong-Hyeon Oh 1 , Ha-Nul Kim 1 , Dieu Nguyen 1<br />

and Ho-Yong Lee 2<br />

1<br />

School <strong>of</strong> Materials Science and Engineering, Chonnam National <strong>University</strong>,<br />

Gwangju 500-757, Republic <strong>of</strong> Korea.<br />

2<br />

Department <strong>of</strong> Advanced Materials Engineering, Sun Moon <strong>University</strong>, Asan,<br />

Chungnam 336-708, Republic <strong>of</strong> Korea.<br />

* E-mail address <strong>of</strong> the corresponding author : johnfisher@jnu.ac.kr<br />

BaTiO3 was one <strong>of</strong> the first piezoelectric ceramics to be discovered, but was quickly<br />

eclipsed by Pb(Zr,Ti)O3. The need for lead-free piezoceramics has caused a renewal <strong>of</strong><br />

interest in BaTiO3 – based systems. Recently, Liu and Wren found that ceramics in the<br />

(Ba,Ca)(Zr,Ti)O3 system have properties comparable to those <strong>of</strong> Pb(Zr,Ti)O3.[1] However,<br />

these ceramics require rather high sintering temperatures <strong>of</strong> 1450-1550�C.[2,3] In this<br />

presentation, the effect <strong>of</strong> TiO2 and CuO addition on the sintering behavior, microstructure,<br />

dielectric and piezoelectric properties <strong>of</strong> (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCTZ) ceramics will be<br />

discussed. BCTZ ceramics were prepared by the mixed oxide route and 1 mol % <strong>of</strong> TiO2 or<br />

CuO was added. Undoped and doped ceramics were sintered at 1350�C and 1400�C for 1-5<br />

hours. CuO was found to be a very effective sintering aid, with samples sintered for 1 hour at<br />

1350�C having a bulk density <strong>of</strong> 95% theoretical density; however the piezoelectric properties<br />

were greatly reduced compared to those in the literature.<br />

[1] Liu W, Ren X Large piezoelectric effect in Pb-free ceramics. Phys Rev Lett 103: 257602 1-4 (2009)<br />

[2] Li W, Xu Z, Chu R, Fu P, Zang G Piezoelectric and dielectric properties <strong>of</strong> (Ba1-xCax)(Ti0.95Zr0.05)O3 leadfree<br />

ceramics. J Am Ceram Soc 93: 2942-44 (2010)<br />

[3] Wang P, Li Y, Lu Y Enhanced piezoelectric properties <strong>of</strong> (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 lead-free ceramics by<br />

optimizing calcination and sintering temperature. J Eur Ceram Soc 31: 2005-2012 (2011)


Contributed<br />

C- 6<br />

16:45 ~ 17:00, August 8<br />

Interfacial Reactions for Co-fired Ni-(Na,K)NbO3 piezoceramics<br />

Ken-ichi Kakimoto, Kensuke Kato and Isao Kagomiya<br />

1 Department <strong>of</strong> Materials Science and Engineering, Graduate School <strong>of</strong> Engineering,<br />

Nagoya Institute <strong>of</strong> Technology, Nagoya 466-8555, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : kakimoto.kenichi@nitech.ac.jp<br />

(Na,K)NbO3–based ceramic system is now studied most intensively from the practical<br />

point <strong>of</strong> view for lead-free piezoelectric transducer application. However, their piezoelectric<br />

properties such as an electrical-field-induced displacement, which is one <strong>of</strong> the important<br />

characters for piezoelectric actuator application, is still much lower than those <strong>of</strong> PZT system.<br />

Under this situation, an importance <strong>of</strong> multilayer structure has been recognized more recently.<br />

On the other hand, (Na,K)NbO3–based ceramic system shows an advantage against PZT<br />

system in the sintering under a reduced atmosphere, which is similar to the case <strong>of</strong> BaTiO3based<br />

multilayer ceramic capacitors (MLCCs). It is therefore expected that non-precious Ni<br />

metals will be adopted as an inner electrode to fabricate cost-effective (Na,K)NbO3–based<br />

multilayer piezoelectric actuators. In general, it has been known that Ni electrodes<br />

demonstrate high electromigration resistance under large electrical fields and excellent<br />

interfacial strengths with ceramic matrix under wide service temperatures, compared with<br />

precious Ag-Pd electrodes used in current PZT actuators. However, there is still in a lack <strong>of</strong><br />

knowledge on the interfacial stability and reaction between Ni and (Na,K)NbO3 during their<br />

co-fired process.<br />

In this work, we studied the chemical stabilities <strong>of</strong> Ni-(Na,K)NbO3 interfaces during heat<br />

treatments processed in reducing atmospheres with various oxygen partial pressures from 10 -<br />

10 -20<br />

atm down to around 10 atm as minimum. The oxidation <strong>of</strong> Ni, a new phase formation,<br />

solid-solution reactions will be reported from the systematic investigations based on various<br />

model experiments. The motivation <strong>of</strong> the present study is to provide a new insight into<br />

possible interfacial reaction pathways based on thermodynamics and defect chemistry.


Contributed<br />

C- 7<br />

11:45 ~ 12:00, August 10<br />

Fabrication <strong>of</strong> lead-free textured (Na0.53K0.47)(Nb0.55Ta0.45)O3 ceramics by<br />

reactive templated grain growth using NaNbO3 templates<br />

A. Hussain 1 , J. S. Kim 1 , G. H. Ryu 1 , T. K. Song 1 , M. H Kim 1* and W. J. Kim 2<br />

1 School <strong>of</strong> Nano & Advanced Materials Engineering, Chanwon National <strong>University</strong>,<br />

Gyeongnam 641-773, Republic <strong>of</strong> Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Gyeongnam 641-773, Republic <strong>of</strong><br />

Korea<br />

* E-mail address <strong>of</strong> the corresponding author : mhkim@changwon.ac.kr<br />

High performance, lead-free piezoelectric ceramics have received considerable research<br />

attention as potential candidate materials for replacements <strong>of</strong> lead-based perovskite, such as<br />

Pb(Zr, Ti)O3 (PZT). In particular, much recent work has focused on (Na, K)NbO3 (NKN)<br />

perovskite system. However, Pure NKN ceramics are difficult to sinter by conventional<br />

methods, and show inferior properties in comparison with PZT. To improve the performance<br />

<strong>of</strong> NKN ceramic system, different techniques for their fabrication such as spark plasma<br />

sintering, screen printing, templated grain growth, and reactive templated growth have been<br />

employed. Among these techniques, the reactive templated grain growth (RTGG) has proved<br />

to be more effective in improving the piezoelectric performance. In this work, we have<br />

synthesized (Na0.53K0.47)(Nb0.55Ta0.45)O3 (NKNT) ceramics by reactive templated grain<br />

growth using plate like NaNbO3 (NN) templates. The NN templates were synthesized from<br />

bismuth layered-structure ferroelectric Bi2.5Na3.5Nb5O18 (BNN) particle by topochemical<br />

microcrystal (TMC) conversion method. The degree <strong>of</strong> grain orientation and the grain<br />

morphologies were examined by XRD and SEM analysis, respectively. We have found that<br />

NKNT grain oriented ceramics prepared by RTGG technique exhibited superior dielectric and<br />

piezoelectric properties than those <strong>of</strong> randomly oriented ceramics.


<strong>Poster</strong> <strong>Session</strong> I<br />

17:00 ~ 18:30, August 8<br />

Gallery, 2F, International Building


<strong>Poster</strong> session I<br />

Increasing Torque <strong>of</strong> One Touch Point Ultrasonic Linear Motor by using<br />

Multilayer Ceramics<br />

Seong Su Jeong 1 , Jung Hoon Lim 1 , Seong Kyu Cheon 1 , Na Lee Kim 1 , Jong Kyu Park 2 ,<br />

Myong Ho Kim 3 and Tae Gone Park 1*<br />

1 Department <strong>of</strong> Electrical Engineering, Changwon <strong>University</strong>, Changwon 641-773, Korea<br />

2 Department <strong>of</strong> Mechanical Engineering, Changwon <strong>University</strong>, Changwon 641-773, Korea<br />

3 School <strong>of</strong> Nano and Advanced Materials Engineering, Changwon <strong>University</strong>, Changwon<br />

641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : tgpark@changwon.ac.kr<br />

In this paper, one touch point ultrasonic linear motor was proposed. The stator <strong>of</strong> the<br />

motor is easy to fabricate because <strong>of</strong> the simple structure and the punching technique. Also,<br />

the thin stator is advantageous to use in tight thin spaces. Metal plate was used as a vibrating<br />

plate <strong>of</strong> the V-shaped stator and four ceramic plates were attached to the upper and lower<br />

surfaces <strong>of</strong> the plate. When two sinusoidal sources with phase difference <strong>of</strong> 90 degrees are<br />

applied to the stator, elliptical displacement is generated at contact tip <strong>of</strong> the stator. Modeling<br />

<strong>of</strong> the ultrasonic motor was done and the displacement characteristics were defined by using<br />

finite element analysis (ATILA). To improve the speed and torque, the ultrasonic motor was<br />

analyzed by changing the angle <strong>of</strong> the legs and using multilayer ceramics. Also, a selected<br />

motor which has large X-axis and Y-axis displacements was fabricated and the speed and<br />

torque <strong>of</strong> the motor were measured.<br />

P- 1


<strong>Poster</strong> session I<br />

Photocurrent behaviours <strong>of</strong> Pt/BNT/Pt and Pt/NKBiT/Pt capacitors<br />

Sung Sik Won, Chang Won Ahn, Won Seok Woo, Song A Chae,<br />

Hae Jin Seog and Ill Won Kim *<br />

Department <strong>of</strong> Physics and Energy Harvest-Storage Research Center, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>,<br />

<strong>Ulsan</strong> 680-749, South Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimiw@mail.ulsan.ac.kr<br />

When ferroelectric materials are illuminated by light beam, voltage and current can be<br />

generated due to separation <strong>of</strong> photoinduced electrons and holes by its internal electric field.<br />

Such photovoltaic phenomena in the ferroelectric thin films exhibit potential applications for<br />

realizing remote control and wireless energy transfer in microelectromechanical system<br />

(MEMS) device. Recently, lead-free ferroelectric materials have been a matter <strong>of</strong> great<br />

interest because <strong>of</strong> the environmental pollution coming from toxic lead based materials. The<br />

Bi0.5Na0.5TiO3 (BNT) and (Na0.82K0.18)0.5Bi4.5Ti4O15 (NKBiT) ferroelectric thin films exhibit<br />

good ferroelectric properties. So, we have investigated the photocurrent behaviours <strong>of</strong> the Pt<br />

sandwiched BNT and NKBiT thin films deposited by chemical solution deposition method.<br />

Ferroelectric P-E hysteresis loops, current-voltage and photocurrent behaviours are discussed.<br />

The mechanism behind the origin <strong>of</strong> the different photocurrent behaviours between Pt/BNT/Pt<br />

and Pt/NKBiT/Pt capacitors was discussed.<br />

P- 2


<strong>Poster</strong> session I<br />

Photovoltaic effect <strong>of</strong> (Na0.82K0.18)0.5Bi4.5Ti4O15 thin film with Pt and<br />

ITO top electrodes<br />

Won Seok Woo, Sung Sik Won, Chang Won Ahn,<br />

Song A Chae and Ill Won Kim *<br />

Department <strong>of</strong> Physics and Energy Harvest-Storage Research Center, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>,<br />

680-749, <strong>Ulsan</strong>, South Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimiw@mail.ulsan.ac.kr<br />

Recent studies revealed that the ferroelectric films exhibited interesting photoelectric<br />

properties in the ultraviolet (UV) regions with the potential applications for energyindependent<br />

memories based on nondestructive optical reading, UV detection and<br />

photovoltaic devices. The layered bismuth structure has a four-layered perovskite unit <strong>of</strong><br />

((Na0.82K0.18)0.5Bi4.5Ti4O13) 2- sandwiched by two (Bi2O2) 2+ layers along the c axis. We have<br />

investigated photoelectric behavior <strong>of</strong> the Pt and ITO top electrodes sandwiched Bi layered<br />

structure (Na0.82K0.18)0.5Bi4.5Ti4O15 (NKBiT15) film deposited by chemical solution<br />

deposition. Based on the analysis <strong>of</strong> the photocurrent and I-V characteristics the Schottky<br />

barrier <strong>of</strong> Pt/film/Pt capacitor displayed symmetric behavior, but that <strong>of</strong> ITO/film/Pt capacitor<br />

exhibited asymmetric behavior. Photovoltaic power conversion efficiency <strong>of</strong> NKBiT15 thin<br />

films with Pt and ITO top electrodes were investigated. The mechanism behind the origin <strong>of</strong><br />

the different photocurrent behaviors between Pt/film/Pt and ITO/film/Pt capacitors was<br />

discussed. The observed photocurrent <strong>of</strong> NKBiT15 films strongly depends on the wavelength<br />

<strong>of</strong> incident light beam. Maximum photocurrent <strong>of</strong> NKBiT15 thin films was obtained at -30.2<br />

nA/cm 2 around 356 nm. The band gap energy <strong>of</strong> the NKBiT15 thin films was 3.4 eV.<br />

P- 3


<strong>Poster</strong> session I<br />

Control <strong>of</strong> Oxygen Vacancies by Plasma Enhanced Atomic Layer<br />

Deposition (PEALD) <strong>of</strong> TiO2 for Memristors<br />

Sang-Joon Park 1,2 , Jeong-Pyo Lee 1 , Jong Shik Jang 1 , Hyun Rhu 1 , Hyunung Yu 1 ,<br />

Byung Youn You 1 , Chang Soo Kim 1 , Kyung Joong Kim 1 , Yong-Jai Cho 1 ,<br />

Sunggi Baik 2 and Woo Lee 1,3*<br />

1 Korea Research Institute <strong>of</strong> Standards and Science (KRISS), Daejeon 305-340, Korea<br />

2 Department <strong>of</strong> Materials Science & Engineering, Pohang <strong>University</strong> <strong>of</strong> Science and<br />

Technology (POSTECH), Pohang 790-784, Korea<br />

3 Department <strong>of</strong> Nano Science, <strong>University</strong> <strong>of</strong> Science and Technology (UST), Yuseong,<br />

Daejeon 305-333, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : woolee@kriss.re.kr<br />

TiOx is one <strong>of</strong> the most extensively studied materials for resistive switching (RS)<br />

applications. It has been generally accepted that the formation and rupture <strong>of</strong> conducting<br />

path(s) <strong>of</strong> oxygen deficient Magnéli phase resulting from field-induced migration and<br />

ordering <strong>of</strong> oxygen vacancies (VO) is mainly responsible for the resistive switching (RS) in<br />

TiOx-based RS devices. In this regard, it is important to investigate the effect <strong>of</strong> oxygen<br />

vacancy concentration on the RS behaviors <strong>of</strong> the TiOx-based memristors. To this end,<br />

Pt/TiOx/Pt capacitors with different values <strong>of</strong> x were prepared. It has been well established<br />

that stoichiometry <strong>of</strong> TiOx was closely related to the oxygen vacancy concentration. TiOx<br />

films were grown by plasma enhanced atomic layer deposition (PEALD) at the substrate<br />

temperature <strong>of</strong> 150 °C. Titanium (IV) tetraisopropoxide (TTIP; Ti[OCH(CH3)2]4) was used as<br />

a Ti precursor. High purity oxygen or mixture gas <strong>of</strong> pure oxygen and nitrogen was adopted<br />

as a reactant during the plasma exposure step. It is noted that the stoichiometry <strong>of</strong> TiOx films<br />

were deliberately controlled from x = 1.62 to 1.70 by adjusting the flow rate ratio (RF) <strong>of</strong> O2<br />

gas to N2 + O2 mixture gas from 0.25 to 1.00. Phases <strong>of</strong> PEALD TiOx films were found to be<br />

amorphous at RF = 0.25, whereas nanocrystalline anatase at RF = 1.00. Confocal Raman<br />

spectroscopic analysis provided an additional evidence for evolution <strong>of</strong> the film crystallinity<br />

with RF,viz., x in TiOx. It was found from the deconvolution <strong>of</strong> the O1s XPS peaks that nonlattice<br />

oxygen content increase from 15.3 to 20.7 % with decreasing the RF from 1.00 to 0.25,<br />

indicating the increases <strong>of</strong> oxygen vacancies in PEALD TiOx film with RF. From<br />

spectroscopic ellipsometry analyses, absorption by the defect states below bandgap increases<br />

with decrease <strong>of</strong> x, i.e., increase <strong>of</strong> oxygen vacancy. The effect <strong>of</strong> oxygen vacancy<br />

concentration on RS behaviors <strong>of</strong> TiOx-based memristors will be discussed in detail in this<br />

presentation.<br />

P- 4


<strong>Poster</strong> session I<br />

Piezoelectric Energy Scavenger based on PZT LTCC Cantilever<br />

Seung Eon Moon 1* , Woo Seok Yang 1 , Jongdae Kim 1 and Yeong Sung Wang 2<br />

1 Nano Convergence Sensor Research Team, Electronics and Telecommunications Research<br />

Institutue, Daejeon 305-700, Korea<br />

2 Lattron, Daejeon 306-230, Korea<br />

* E- mail address <strong>of</strong> the corresponding author : semoon@etri.re.kr<br />

In this paper, we present the results <strong>of</strong> a preliminary study on the piezoelectric energy<br />

scavenging performance <strong>of</strong> a PZT low temperature co-firing ceramic (LTCC) beam. A novel<br />

piezoelectric beam cantilever structure is used to demonstrate the feasibility <strong>of</strong> generating AC<br />

voltage during a state <strong>of</strong> vibration. The energy-scavening capability <strong>of</strong> a PZT LTCC beam is<br />

tested. The frequency response <strong>of</strong> the cantilever device shows that the first mode resonance<br />

frequency <strong>of</strong> the excitation model exists in the neighborhood <strong>of</strong> several hundreds <strong>of</strong> hertz.<br />

These tests show that a few open AC voltages and sub-mW power are achieved. To test the<br />

possibility <strong>of</strong> a small scale power source for a ubiquitous sensor network service, energy<br />

conversion and the testing <strong>of</strong> storage experiment are also carried out.<br />

P- 5


<strong>Poster</strong> session I<br />

Lead-free alkaline niobates nanostructures for piezoelectric nanogenerators<br />

Byung Kil Yun 1 , Jong Hoon Jung 1* and Zhong Lin Wang 2<br />

1 Department <strong>of</strong> Physics, Inha <strong>University</strong>, Incheon 402-751, Korea<br />

2 School <strong>of</strong> Materials Science and Engineering, Georgia Institute <strong>of</strong> Technology, Atlanta, GA<br />

30332, USA<br />

* E-mail address <strong>of</strong> the corresponding author : jhjung@inha.ac.kr<br />

Perovskite ferroelectric nanowires have rarely been used for the conversion <strong>of</strong> tiny<br />

mechanical vibrations into electricity, in spite <strong>of</strong> their large piezoelectricity. Here we present<br />

the lead-free alkaline ferroelectric nanowires based piezoelectric device for the high output<br />

and cost-effective flexible nanogenerator. The device consists <strong>of</strong> a alkaline niobates<br />

nanostructures-poly(dimethylsiloxane) polymer composite and Au/Cr coated polymer films.<br />

High quality alkaline niobates nanowires/nanorods can be grown by hydrothermal method at<br />

low temperature and can be poled by an electric field at room temperature. The composite<br />

device shows an output voltage <strong>of</strong> ~3.0 V and output current <strong>of</strong> ~70 nA under a small<br />

compressive strain. These results imply that alkaline niobates ferroelectric nanostructures<br />

should be quite useful for the lead-free piezoelectric nanogenerator applications.<br />

P- 6


<strong>Poster</strong> session I<br />

Transient Negative Capacitance in Domain Wall <strong>of</strong> Ferroelectric Thin<br />

Films<br />

Yu Jin Kim 1* , Min Hyuk Park 1 , Han Joon Kim 1 , Doo Seok Jeong 2 , Anquan Jiang 3<br />

and Cheol Seong Hwang 1<br />

1 WCU Hybrid Materials Program, Department <strong>of</strong> Material Science & Engineering and Interuniversity<br />

Semiconductor Research Center, Seoul National <strong>University</strong>, Republic <strong>of</strong> Korea<br />

2 Electronic Materials Center, Korea Institute <strong>of</strong> Science and Technology, Republic <strong>of</strong> Korea<br />

3 State Key Laboratory <strong>of</strong> ASIC & System, Department <strong>of</strong> Microelectronics, Fudan<br />

<strong>University</strong>, Shanghai, 200433, China<br />

* E-mail address <strong>of</strong> the corresponding author : uzinknig@snu.ac.kr<br />

The bi-stable polarization states <strong>of</strong> ferroelectric (FE) materials received a great deal <strong>of</strong><br />

attention for its application to electronic devices. Especially, one <strong>of</strong> the most intriguing topics<br />

<strong>of</strong> ferroelectric application in recent years is the involvement <strong>of</strong> the negative capacitance<br />

(NC) effect in the ferroelectrics in FE – dielectrics (DE) stacked system. [1] If NC effect is<br />

stably obtained, it may revolutionize the electronic devices because capacitance is not a<br />

simple linear function <strong>of</strong> area anymore. Furthermore, voltage can be amplified without using<br />

external circuit. This means that the conventional scaling rule for semiconductor devices must<br />

be changed. However, this can be fundamentally difficult because <strong>of</strong> the very high tendency<br />

<strong>of</strong> domain formation in ferroelectric thin film system; especially the FE-DE system could<br />

involve a serious depolarization effect which pr<strong>of</strong>oundly favors the poly-domain structure.<br />

In this work, the authors observed NC effect from the domain wall <strong>of</strong> ferroelectric thin<br />

film in a FE-DE stacked system. It is considered that the physical state <strong>of</strong> domain wall region<br />

is prone to show NC because P ~ 0 there but still the crystal structure is the same as FE bulk.<br />

In normal FE switching, the domain propagation is generally quite fast, so observing the<br />

electric response <strong>of</strong> the domain wall regions is rather difficult. Therefore, the authors<br />

designed several FE-DE systems where the DE controls the compensating charge injection to<br />

an appropriate level and enhance the chance to see the responses <strong>of</strong> domain boundaries to the<br />

electric pulses. This must be a thermodynamically reasonable result considering polarization<br />

compensated charge contribution to the Landau’s phenomenological model. Detailed<br />

experimental and model study results will be presented.<br />

[1] S. Salahuddin and S. Datta, Nano Lett. 8, 405 (2008)<br />

P- 7


<strong>Poster</strong> session I<br />

Enhanced Dielectric and Piezoelectric Properties <strong>of</strong> BaTiO3-Based Single<br />

Crystals by Defect-Polarization Control<br />

Shotaro Ishikawa 1* , Yuuki Kitanaka 1 , Takeshi Oguchi 1 , Yuji Noguchi 1 ,<br />

Masaru Miyayama 1 , Chikako Moriyoshi 2 and Yoshihiro Kuroiwa 2<br />

1 Research Center for Advanced Science and Technology, The <strong>University</strong> <strong>of</strong> Tokyo, 4-6-1<br />

Komaba, Meguro-ku, Tokyo 153-8904, Japan<br />

2 Department <strong>of</strong> Physical Science, Hiroshima <strong>University</strong>, Kagamiyama, Higashi-Hiroshima,<br />

Hiroshima 739-8526, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : s-ishikawa@crm.rcast.u-tokyo.ac.jp<br />

Ferroelectric-related properties are governed by domain structures and their dynamics<br />

with respect to electric field, [1] which is greatly influenced by lattice defects. [2] Defect<br />

chemistry <strong>of</strong> barium titanate (BaTiO3: BT) is dominated by acceptor impurities that are<br />

inevitably present in raw materials. [2] It has been reported that dielectric and piezoelectric<br />

properties for thin films or ceramics <strong>of</strong> BT and Pb-based ferroelectrics are improved by the<br />

doping <strong>of</strong> acceptors such as Mn, [3] but the details <strong>of</strong> the defect structure are not clear. To<br />

develop materials design <strong>of</strong> ferroelectrics, it is considered essential to control the domain<br />

dynamics based on the defect chemistry. The aim <strong>of</strong> this study is to establish materials design<br />

for enhancing dielectric and piezoelectric properties based on “defect-polarization control”.<br />

The defect-polarization control is defined as the domain engineering based on defect<br />

chemistry, in which the strong attractive interaction between domain walls and oxygen<br />

vacancies [4] are utilized to stabilize nanometer sized domains. Here, BT is chosen as a model<br />

material and the single crystals <strong>of</strong> BT-based materials were used for evaluations.<br />

Mn-doped BT single crystals were grown by a top-seeded solution growth (TSSG)<br />

method in air. Crystals with 14×14×11 mm 3 size were obtained (Fig. 1). Mn (0.1 %)-doped<br />

BT crystals (Mn-BT) showed a piezoelectric strain constant d33 along cubic <strong>of</strong> 630 pm/V<br />

(Fig. 2.), which was much larger than those <strong>of</strong> undoped BT crystals and single-domain BT<br />

crystals (86 pm/V [5] ). Piezoresponse-force microscope observations showed that Mn-BT<br />

poled along cubic had a peculiar domain structure with a size <strong>of</strong> 20-40 nm. In-situ<br />

synchrotron X-ray diffraction analysis indicated that Mn-BT has the tetragonal P4mm<br />

structure regardless <strong>of</strong> electric filed whereas undoped BT crystals undergo an electric-field-<br />

induced phase transition from the tetragonal P4mm to orthorhombic or monoclinic structures.<br />

[1] S. Wada. et al.,<br />

Ferroelectrics, 334, 17<br />

(2006).[2] D. M. Smith.<br />

et al., J. Am. Ceram. Sci.,<br />

0.06<br />

0.04<br />

64, 9 (1981).[3] H. Kishi.<br />

et al., Jpn. J. Appl. Phys.,<br />

39, 5533 (2000).[4] Y.<br />

Kitanaka. et al., Phys.<br />

Rev. B 81, 094114 (2010).<br />

[5] D. Berlincourt et al.,<br />

Phys. Rev., 111, 143<br />

(1958).<br />

0.02<br />

0.00<br />

0 2 4 6 8 10<br />

Electric Field /kVcm �1<br />

c<br />

25 ℃ 1 Hz<br />

E // c<br />

x = 0.1 %<br />

14 mm<br />

Fig.1 The photo <strong>of</strong> 0.5 % Mndoped<br />

BT crystals obtained by<br />

a TSSG method.<br />

x = 0 % (BT)<br />

Fig.2 Piezoelectric strain <strong>of</strong><br />

0.1 % Mn-doped BT crystals<br />

and BT crystals.<br />

P- 8<br />

Strain / %


<strong>Poster</strong> session I<br />

Influence <strong>of</strong> 60 o domain structure on orthorhombic niobate-based<br />

piezoelectric property<br />

Kohei Tsuchida * , Ken-ichi Kakimoto and Isao Kagomiya<br />

Department <strong>of</strong> Materials Science and Engineering, Graduate School <strong>of</strong> Engineering, Nagoya<br />

Institute <strong>of</strong> Technology, Nagoya 466-8555, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : cjk15059@stn.nitech.ac.jp<br />

Lead-free (Na,K)NbO3 (NKN)-based ceramics have been expected to be applied to<br />

sensors and actuators at high temperature because <strong>of</strong> their relatively good piezoelectric<br />

property and high Curie temperature. However, their piezoelectric properties are not well over<br />

Pb(Zr,Ti)O3(PZT)-based ceramics. In addition, NKN ceramics show difficulty and less<br />

reproducibility to prepare high density samples by a conventional solid-state reaction under<br />

atmospheric pressure. Therefore, the advancement <strong>of</strong> the sinterability and electric properties<br />

by the improvement <strong>of</strong> sintering and synthesis process has been investigated. In contrast, the<br />

study <strong>of</strong> ferroelectric domains <strong>of</strong> NKN ceramics is not enough to be investigated, and this is<br />

necessary for better understanding and improvement <strong>of</strong> their inherent properties.<br />

In the case <strong>of</strong> PZT ceramics, the change <strong>of</strong> domain structure during poling process was<br />

clearly discussed and the influence <strong>of</strong> 90 o domain structure on the strain was well known.<br />

NKN ceramics belong to the space group <strong>of</strong> orthorhombic Bmm2 which show a lower<br />

symmetric structure than tetragonal P4mm PZT ceramics at room temperature. Therefore,<br />

NKN ceramics show a complex domain structure including 60 o domains besides 90 o domains.<br />

However, there have been only a few detailed reports on the change <strong>of</strong> domain structure under<br />

applied electrical field on NKN ceramics.<br />

In this study, we evaluated the response <strong>of</strong> 90 o and 60 o domain structures under applied<br />

electrical fields on NKN ceramics. For NKN crystal, the amount <strong>of</strong> strain that is induced by<br />

domain switching was attributed to their direction <strong>of</strong> spontaneous polarization <strong>of</strong> 90 o and 60 o<br />

domain structures. Therefore, we now advance in the study <strong>of</strong> the domain dynamics based on<br />

changes <strong>of</strong> crystallite orientation under various poling fields by using an X-ray diffraction<br />

method and electrical-field induced strain <strong>of</strong> NKN ceramics. As a result, we firstly found an<br />

advantage <strong>of</strong> orthorhombic NKN ceramics on thermal dependence <strong>of</strong> their piezoelectric<br />

property.<br />

P- 9


<strong>Poster</strong> session I<br />

Nanoscale visualization <strong>of</strong> domain wall pinning process as the origin <strong>of</strong><br />

polarization fatigue<br />

Yeong Jae Shin 1* , Sang Mo Yang 1 , Tae Heon Kim 1 , Jong-Gul Yoon 2<br />

and Tea Won Noh 1<br />

1 ReCFI, Department <strong>of</strong> Physics and Astronomy, Seoul National <strong>University</strong>, Seoul 151-747,<br />

Korea<br />

2 Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> Suwon, Hwaseong, Gyunggi-do 445-743, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : yjshin@phya.snu.ac.kr<br />

The microscopic mechanism <strong>of</strong> polarization fatigue (i.e., a loss <strong>of</strong> switchable<br />

polarization under electrical cycling) remains one <strong>of</strong> the most important long-standing<br />

problems in ferroelectric communities. Although there are numerous proposed fatigue models,<br />

a consensus between the models and experimental results is not reached yet.<br />

Here, we present the visualization <strong>of</strong> nanoscale domain switching dynamics for different<br />

fatigue stages in epitaxial PbZr0.4Ti0.6O3 capacitors by using modified-piezoresponse force<br />

microscopy [1]. Systematic time-dependent studies <strong>of</strong> the domain nucleation and evolution<br />

allow us to find that domain wall pinning, rather than nucleation inhibition, is the primary<br />

origin <strong>of</strong> fatigue. Especially, we can directly observe the evolution <strong>of</strong> domain wall pinning<br />

process during electrical cycling, from the suppression <strong>of</strong> sideways domain growth in early<br />

fatigued stages to the blockage <strong>of</strong> forward domain growth in later stages.<br />

Reference: [1] S. M. Yang et al., Adv. Funct. Mater. (2012), published online.<br />

P- 10


<strong>Poster</strong> session I<br />

Preparation <strong>of</strong> Epitaxial BiFeO3 Thin Films on La-SrTiO3 Substrate by<br />

Magnetic-Field-Assisted Pulsed Laser Deposition<br />

Jung Min Park 1 *, S. Nakashima 2 , M. Sohgawa 1 , T. Kanashima 1 and M. Okuyama 3<br />

1 Graduate School <strong>of</strong> Engineering Science, Osaka <strong>University</strong>, Osaka 560-8531, Japan<br />

2 Graduate School <strong>of</strong> Engineering, <strong>University</strong> <strong>of</strong> Hyogo, Hyogo 671-2201, Japan<br />

3 Institute for NanoScience Design, Osaka <strong>University</strong>, Osaka 560-8531, Japan<br />

* E-mail address <strong>of</strong> the corresponding author: jmpark@semi.ee.es.osaka-u.ac.jp<br />

Bismuth ferrite (BiFeO3, BFO) is well known as a multiferroic material, exhibiting<br />

ferroelectric and anti-ferromagnetic properties. In particular, epitaxial BFO thin film on<br />

SrTiO3 (STO) substrate prepared by a pulsed laser deposition (PLD) has large polarization<br />

value (55 µC/cm 2 ) at RT. 1) Recently, good epitaxial BFO thin films have been prepared on<br />

vicinal STO substrate with various deposition methods such as MOCVD and <strong>of</strong>f-axis<br />

sputtering. 2) In this study, we have prepared epitaxial BFO thin film by using magnetic field<br />

assisted PLD method as a new deposition method, having a high deposition rate due to<br />

modification <strong>of</strong> ion trajectory under magnetic field. 3)<br />

Magnet was set between the target and the substrate in the vacuum chamber, and<br />

magnetic field was applied perpendicularly to the substrate during film deposition. Epitaxial<br />

BFO thin films were prepared on La (3.75 wt%)-doped STO single crystal substrate <strong>of</strong><br />

conductive electrode at a substrate temperature <strong>of</strong> 700 o C and O2 pressure <strong>of</strong> 0.02 ~ 0.1 Torr<br />

under magnetic field <strong>of</strong> 0, 0.1, and 0.4 T.<br />

XRD patterns <strong>of</strong> epitaxial BFO thin films prepared under 0, 0.1, and 0.4 T show only the<br />

(001) diffraction peaks without secondary phases. From result <strong>of</strong> reciprocal space mapping<br />

(RSM), (003) planes for epitaxial BFO thin films prepared under 0, 0.1 and 0.4 T show peak<br />

splitting and lattice parameters <strong>of</strong> out <strong>of</strong> plane were 0.397, 0.397 and 0.396 nm, respectively.<br />

Moreover, peak splitting <strong>of</strong> (103) and (-103) reflection is observed and lattice parameters <strong>of</strong><br />

in-plane in rhombohedral structure were 0.397, 0.397, and 0.396 nm for the films prepared<br />

under 0, 0.1, and 0.4 T, respectively. P-E hysteresis loop in all the epitaxial films was<br />

obtained at RT and remanent polarization (Pr) <strong>of</strong> the film prepared under 0.1 T was 46<br />

µC/cm 2 , while current density was reduced in an epitaxial BFO thin film prepared under 0.1 T.<br />

1) J. Wang et al., Science 299 1719 (2003)<br />

2) R. Ramesh, and C. B. Eom et al., Phase transitions 79 991 (2006)<br />

3) J. M. Park et al., Jpn. J. Appl. Phys. 50 09NB03 (2011)<br />

P- 11


<strong>Poster</strong> session I<br />

Equilateral triangle closure domains in (111)-oriented epitaxial<br />

PbZr0.35Ti0.65O3 thin films<br />

Sang Mo Yang 1* , Young Jae Shin 1 , Hiroshi Funakubo 2 , Jong-Gul Yoon 3 ,<br />

James F. Scott 4 , and Tae Won Noh 1<br />

1 ReCFI, Department <strong>of</strong> Physics and Astronomy, Seoul Nat’l Univ., Seoul 151-747, Korea<br />

2 Dept. <strong>of</strong> Innovative and Engineered Material, Tokyo Institute <strong>of</strong> Technology,<br />

Yokohama 226-8503, Japan<br />

3 Dept. <strong>of</strong> Physics, Univ. <strong>of</strong> Suwon, Hwaseong, Gyunggi-do 445-743, Korea<br />

4 Dept. <strong>of</strong> Physics, Cavendish Laboratory, Univ. <strong>of</strong> Cambridge, Cambridge CB3 0HE, UK<br />

* E-mail address <strong>of</strong> the corresponding author : smyang@phya.snu.ac.kr<br />

Topological defects in ferroelectrics and multiferroics have attracted significant attention<br />

both as a playground <strong>of</strong> exotic physical phenomena and for potential applications in<br />

reconfigurable electronic devices [1]. One example <strong>of</strong> such topological defects is a flux-closure<br />

domain. The flux-closure domain in ferroics indicates the arrangements <strong>of</strong> local order parameters,<br />

which are rotated continuously with satisfying the head-to-tail alignment. The driving force<br />

behind the formation <strong>of</strong> flux-closure domain states is the minimization <strong>of</strong> depolarizing or<br />

demagnetizing fields, achieved through the creation <strong>of</strong> head-to-tail dipolar or magnetic loops.<br />

While these intriguing domain patterns are commonly observed in ferromagnetics, its existence in<br />

ferroelectrics is not yet well established and understood. Quite recently, a burgeoning interest in<br />

ferroelectric as well as multiferroic closure domain states has developed, leading to a pr<strong>of</strong>usion <strong>of</strong><br />

both theoretical and experimental studies [2].<br />

Here, we report on the observation <strong>of</strong> novel topological defect structure and investigation <strong>of</strong><br />

its electrical properties in the 3-fold rotational symmetry ferroelectric system. We explored<br />

nanoscale ferroelectric domain configurations in 160 nm (111)-oriented epitaxial PbZr0.35Ti0.65O3<br />

films by using piezoresponse force microscopy. After out-<strong>of</strong>-plane polarization switching by a<br />

poling process, we observed a very intriguing change <strong>of</strong> ferroelectric in-plane domains, i.e., the<br />

formation <strong>of</strong> equilateral triangle closure domains. Using conductive-atomic force microscopy, we<br />

investigated the local electric conductivities <strong>of</strong> this exotic topological defect structure, and found<br />

that the intersection point <strong>of</strong> domain walls (called vertex) exhibits significant electric<br />

conductivities compared with the surrounding regions.<br />

[1] N. Balke et al., Nature Physics 8, 81 (2012).<br />

[2] G. Catalan et al., Review <strong>of</strong> Modern Physics 84, 119 (2012).<br />

P- 12


<strong>Poster</strong> session I<br />

Effect <strong>of</strong> Composition on the ferroelectric properties <strong>of</strong> HfxZr1-xO2 thin film<br />

Han Joon Kim 1* , Min Hyuk Park 1 , Yu Jin Kim 1 , Hyo Kyeom Kim 1 , Il-Hyuk Yu 1<br />

and Cheol Seong Hwang 1<br />

1 WCU Hybrid Materials Program, Department <strong>of</strong> Material Science & Engineering and Interuniversity<br />

Semiconductor Research Center, Seoul National <strong>University</strong>, Seoul 151-744, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : june110@snu.ac.kr<br />

Ferroelectric random access memory (FeRAM), and Ferroelectric Field-Effect-<br />

Transistor (FeFET) have been regarded as the most promising universal non-volatile<br />

memories due to its reversibly bi-stable polarization states. Most <strong>of</strong> the former researches<br />

have focused on the material system based on the perovskite structure. However, such system<br />

suffers from several problems; the size effect, difficult fabrication process, relatively small<br />

bandgap, and very high dielectric constant. As a result, the development <strong>of</strong> very high density<br />

FeRAM has been deterred and other emerging memories, such as PcRAM, ReRAM, and<br />

MRAM, attracts a greater deal <strong>of</strong> attention at the moment. However, it was recently reported<br />

that HfO2 can show ferroelectric properties when doped with various dopants such as Si, Y,<br />

Al, and Zr. [1-2] This could revolutionize the field <strong>of</strong> ferroelectrics. Due to its small thickness<br />

and matured atomic layer deposition technique, Hf based ferroelectrics can be compatible<br />

with conventional Si technology and appropriate for 3-D capacitor. Among various dopants,<br />

Zr seems to be the most promising which has almost identical chemical property as that <strong>of</strong> Hf.<br />

However, there has not been a systematic report on the effect <strong>of</strong> composition on the<br />

ferroelectric properties <strong>of</strong> HfxZr1-xO2 (HZO) films. In this presentation, HZO capacitors with<br />

various compositions were fabricated and its electrical characteristics will be reported. It was<br />

confirmed that HZO system show ferroelectric property in a wide range <strong>of</strong> compositions, and<br />

samples with stoichiometric Hf0.5Zr0.5O2 showed the largest Pr values and most square-shaped<br />

P-V curves. With increasing the Zr composition, Pr and dielectric constant decreased and antiferroelectric<br />

appears. In Hf-rich condition, on the other hand, the same result was obtained,<br />

but with no anti-ferroelectric behaviour. The structure <strong>of</strong> HfxZr1-xO2 film changes from<br />

orthorhombic to tetragonal (monoclinic) when x decreases (increases) below 0.5. Other<br />

ferroelectric parameters depending on the various compositions will also be reported.<br />

[1] T. S. Böscke, J. Müller, D. Bräuhaus, U. Schröder, and U. Böttger, Appl. Phys. Lett. 2011 ,<br />

99 , 102903.<br />

[2] J. Müller , T. S. Böscke , D. Bräuhaus , U. Schröder , U. Böttger , J. Sundqvist , P.<br />

Kücher , T. Mikolajick , and L. Frey , Appl. Phys. Lett. 2011 , 99 , 112901.<br />

P- 13


<strong>Poster</strong> session I<br />

Phase effect <strong>of</strong> the polycrystalline BiFeO3 thin film by puled laser<br />

deposition<br />

H. I. Choi 1 , M. H. Lee 2 , S. W. Kim 1 , W. J. Kim 1* , J. S. Park 2 , D. J. Kim 2 , D. Do 2 ,<br />

T. K. Song 2 and M. H. Kim 2<br />

1 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon 641-773, Korea<br />

2 School <strong>of</strong> Nano & Advenced Material Engneering, Changwon National Univerisity,<br />

Changwon 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kwj@changwon.ac.kr<br />

The bismuth ferrite, BiFeO3 (BFO), is one <strong>of</strong> the candidate materials for ferroelectric<br />

memory and electronic device applications. It has two important physical aspects,<br />

ferroelectric and magnetic properties, simultaneously. Recently, many other research groups<br />

were improving the ferroelectric property by texturing effect such as oxide electrode. In this<br />

presentation, the BFO thin films have been deposited by a pulsed laser deposition method on<br />

the Pt/Ti/SiO2/Si substrate with different deposition temperature. Structural and electrical<br />

properties <strong>of</strong> the thin films were investigated by an x-ray diffractometer and electrical<br />

electrometer to measure leakage currents and ferroelectric properties. It was exhibited that the<br />

hysteresis loop <strong>of</strong> BFO-P (polycrystalline film) and BFO-T ((111)-textured film) were 64<br />

μC/cm 2 and 128 μC/cm 2 with coercive electric field at 618 kV/cm and 680 kV/cm within<br />

applied electric field at 700 kV/cm.<br />

P- 14


<strong>Poster</strong> session I<br />

The role <strong>of</strong> defect-dipole in BiFeO3 thin films<br />

Myang Hwan Lee 1 , Jin Su Park 1 , Da Jeong Kim 1 , Dalhyun Do 1 , Myong-Ho Kim 1 ,<br />

Sang Wook Kim 2 , Hae In Choi 2 , Sang Su Kim 2 , Won Jeong Kim 2<br />

and Tae Kwon Song 1*<br />

1 School <strong>of</strong> Nano and Advanced Material Engineering, Changwon National<strong>University</strong>,<br />

Changwon 641-773, Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon 641-773,Korea<br />

* E-mailaddress <strong>of</strong> the corresponding author : tksong@changwon.ac.kr<br />

Multiferroic BiFeO3 (BFO) thin films are one <strong>of</strong> the candidate materials for new<br />

functional memory applications. However, BFO have drawbacks, such as a high leakage<br />

current density and poor ferroelectric properties <strong>of</strong>ten observed in BFO thin films because <strong>of</strong><br />

defects and chemical nonstoichiometry. In order to improve the leakage current and<br />

ferroelectric properties, substitutions <strong>of</strong> Bi to lanthanides and/or Fe to 3d transition metals<br />

have been extensively investigated.<br />

In this work, the Bi1.05(Fe0.99R0.01)O3 (R=Mn 2+ , Zn 2+ , Mn 4+ , and Ti 4+ ) films were<br />

deposited on Pt(111)/Ti/SiO2/Si(100) substrates by pulsed laser deposition. The effects <strong>of</strong> the<br />

substitution <strong>of</strong> ions with different oxidation states on ferroelectric and leakage current<br />

properties <strong>of</strong> those films will be discussed.<br />

P- 15


<strong>Poster</strong> session I<br />

Flexoelectric Reversal <strong>of</strong> Polarization in Epitaxial BiFeO3 Films<br />

Byung Chul Jeon 1* , Daesu Lee 1 , Tae Heon Kim 1 , Sang Mo Yang 1 , Myang Hwan Lee 2 ,<br />

Yong Su Kim 1 , Tae Kwan Song 2 , Jong Gul Yoon 3 , Jin Suk Jeong 4 and Tae Won Noh 1<br />

1 ReCFI, Department <strong>of</strong> Physics and Astronomy, Seoul National <strong>University</strong>, Seoul 151-747<br />

2 School <strong>of</strong> Nano and Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Changwon 641-773<br />

3 Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> Suwon, Hwaseong, Gyunggi-do 445-743<br />

4 Department <strong>of</strong> Physics, Soongsil <strong>University</strong>, Seoul 156-743, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : redwolfy@gmail.com<br />

The exploration <strong>of</strong> strain for modifying and improving physical properties <strong>of</strong> thin films<br />

is the aim <strong>of</strong> strain engineering, which has by now become a very popular discipline. Of equal<br />

interest but generally more overlooked is the fact that strain gradients can also affect<br />

functional properties, through the mechanism <strong>of</strong> flexoelectricity. Owing to their universal<br />

nature, strain gradients and flexoelectricity have been already shown to have important effects<br />

on various material systems. The vertical and horizontal direction <strong>of</strong> strain gradients generate<br />

a horizontal flexoelectricity that forces the spontaneous polarization to rotate away from the<br />

normal. [Nat. Mater. 16, 963 (2011)] Furthermore, Lee at al., were realized the giant<br />

flexoelectric effect in epitaxial HoMnO3 thin films. It was proposed that flexoelectric effect<br />

should be the intrinsic effect in all dielectric materials. [Phys. Rev. Lett. 105, 127601 (2010)]<br />

In this presentation, we demonstrate the flexoelectric effect (strain gradient induced<br />

polarization) in BiFeO3 films. We synthesized the fully-strained and -relaxed BiFeO3 films on<br />

vicinal SrTiO3(001) films along the [010] direction varying the deposition temperatures. In<br />

the published literatures, as-grown polarization direction in BiFeO3 films is downward. [Adv.<br />

Mater. 19, 2662 (2007), Nat. Mater. 28, 309 (2010)] As-grown polarization direction for<br />

fully-relaxed (-strained) BiFeO3 film is upward (downward). Flexoelectric field is generated<br />

by these relaxation (strain gradient), which reversed the as-grown polarization direction. The<br />

origin <strong>of</strong> self-poling effect in BiFeO3/SrRuO3 geometry film might be explained by<br />

flexoelectric effect.<br />

P- 16


<strong>Poster</strong> session I<br />

Morphology studies <strong>of</strong> poly(vinylidene fluoride-trifluoroethylene)<br />

copolymer films<br />

Hyeon Jun Lee 1 and Ji Young Jo 1*<br />

1 School <strong>of</strong> Materials Science and Engineering, Gwangju Institute <strong>of</strong><br />

Science and Technology, Gwangju 500-712<br />

* E-mail address <strong>of</strong> the corresponding author : jyjo@gist.ac.kr<br />

Poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer is a highly<br />

ferroelectric organic material with origin <strong>of</strong> ferroelectricity arising from crystalline beta phase.<br />

Ferroelectric phase <strong>of</strong> P(VDF-TrFE) can be achieved by annealing at the temperature higher<br />

than Curie temperature, which leads to rough morphology due to nano-rods structure and<br />

voids during crystallization process. Rough morphology has been reported to result in<br />

degradation <strong>of</strong> ferroelectric properties. However, there have been rare studies to improve the<br />

roughness <strong>of</strong> P(VDF-TrFE) films yet. In this study, we developed experiment method to<br />

improve morphology <strong>of</strong> P(VDF-TrFE) thin films using double coating method.<br />

P(VDF-TrFE) thin films are firstly coated on indium tin oxide/ glass substrates using<br />

spin coating technique. After the annealing at 120℃, the sample soaked in P(VDF-TrFE)<br />

solution at various temperature and time is spin-coated again. Double coated samples show<br />

increase <strong>of</strong> diameter <strong>of</strong> nano-rods and consequently decrease <strong>of</strong> the size <strong>of</strong> void. We found<br />

that surface roughness <strong>of</strong> a double-coated sample in root mean square value is improved by<br />

up to 3 times than that <strong>of</strong> single coated sample.(20 nm to 6 nm) In this presentation, we will<br />

discuss the ferroelectric properties related to the morphology <strong>of</strong> P(VDF-TrFE) thin films.<br />

P- 17


<strong>Poster</strong> session I<br />

Measurement <strong>of</strong> transverse piezoelectric coefficient in the <strong>of</strong><br />

Bi0.5(Na0.82K0.18)0.5TiO3 lead-free films<br />

Song A Chae, Chang Won Ahn, Kang Ho Choi and Ill Won Kim *<br />

Department <strong>of</strong> Physics and Energy Harvest-Storage Research Center, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>,<br />

<strong>Ulsan</strong>, South Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimiw@mail.ulsan.ac.kr<br />

The most widely used piezoelectric materials are lead oxide based Pb(Zr,Ti)O3 (PZT)<br />

materials. PZT material exhibits high piezoelectric properties close to a morphotropic phase<br />

boundary (MPB) between rhombohedral and tetragonal phases. Nevertheless, the most used<br />

PZT materials can contain up to 60% lead by weight ratio. Due to the high toxicity <strong>of</strong> lead,<br />

there is significant interest in developing lead-free piezoelectric materials. Lead-free<br />

piezoelectric materials exhibiting superior electromechanical responses have been formulated<br />

near the MPB region. Among the lead-free piezoelectric materials so far developed, the<br />

binary (1-x)BNT-xBKT (BNKT) class <strong>of</strong> materials has received considerable attention due to<br />

its excellent ferroelectric and piezoelectric properties near the rhombohedral-tetragonal MPB<br />

with 0.16≤ x ≤ 0.20.<br />

The main hindrance <strong>of</strong> BNKT thin films fabrication is the loss <strong>of</strong> stoichiometry because<br />

K is very sensitive to humidity and easy to volatilize during the thermal process. In this study,<br />

we have deposited Bi0.5(Na0.82K0.18)0.5TiO3 thin films having submicron meter thickness on<br />

Pt(111)/TiO2/SiO2/Si(100) substrates by using the chemical solution deposition method. This<br />

films were annealed from 700 to 750 o C for 1 h in the oxygen atmosphere to convert<br />

amorphous to BNKT phase. We have investigated the effect <strong>of</strong> various excess (10 ~ 140<br />

mol%) <strong>of</strong> K in precursor solution by measuring on the surface morphology, crystal structure<br />

and transverse piezoelectric coefficient.<br />

P- 18


<strong>Poster</strong> session I<br />

Electrical Properties <strong>of</strong> Compositionally Modulated Ferroelectric<br />

Pb(Zr,Ti)O3 Multilayer Films<br />

Sung Min Seo and Jong-Gul Yoon<br />

Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> Suwon, Hwaseong 445-743, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : jgyoon@suwon.ac.kr<br />

We investigated electrical properties <strong>of</strong> ferroelectric Pb(Zr,Ti)O3 (PZT) multilayer films<br />

<strong>of</strong> which the layers had different Zr/Ti ratios and thicknesses. The compositionally<br />

modulated PZT multilayer films were prepared by chemical solution deposition. Since the<br />

electrical properties <strong>of</strong> PZT material, such as remnant polarization and coercive<br />

fields, strongly depend on the Zr/Ti ratio, the compositional modulation in the multilayer<br />

films may have discontinuity in the electrical properties at the interfaces and induces their<br />

unique characteristics. Polarization-voltage hysteresis loop and capacitance-voltage<br />

characteristics <strong>of</strong> the compositionally modulated multilayer films were compared with those<br />

<strong>of</strong> conventional films <strong>of</strong> uniform composition. The compositionally modulated multilayer<br />

films showed better electrical characteristics, such as higher remnant polarization, lower<br />

coercive fields and higher dielectric responses, than those <strong>of</strong> single layer films. We will<br />

discuss the electrical properties and usefulness <strong>of</strong> the compositionally modulated ferroelectric<br />

films.<br />

P- 19


<strong>Poster</strong> session I<br />

Studies on photovoltaic effect <strong>of</strong> PZT thin film capacitors depending on Zr/Ti<br />

ratio<br />

Chang Jo Han 1 and Ji Young Jo 1*<br />

1 School <strong>of</strong> Materials Science and Engineering, Gwangju Institute <strong>of</strong> Science and Technology,<br />

Gwangju 500-712, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: jyjo@gist.ac.kr<br />

Ferroelectric thin films <strong>of</strong>fer the opportunities for photovoltaic devices because internal<br />

electric field arising from remnant polarization contributes to flow <strong>of</strong> photocurrent under<br />

exposure to light. Pb(Zr,Ti)O3 (PZT) exhibits the highest remnant polarization value which<br />

dramatically changes depending on Zr/Ti ratio. The Zr/Ti ratio is well known to affect the<br />

structural/electrical properties <strong>of</strong> PZT thin films including grain size, orientation, coercive<br />

voltage, and dielectric constant as well as remnant polarization. However, there have been<br />

few studies on how these properties affect photovoltaic effect systematically. Here, we report<br />

the relationship between photovoltaic effect and Zr/Ti ratio.<br />

PZT thin films were deposited on indium tin oxide/glass substrates using spin coating<br />

method. With the Zr/Ti ratio in a range from 20/80 to 80/20, sol–gel solutions were prepared<br />

with lead acetate tri-hydrate [Pb(CH3CO2)2-3H2O], zirconium n-propoxide [Zr(C3H7O)4(n-<br />

propoxide)], and titanium isopropoxide [((CH3)2CHO)4(i-Ti)] precursors by dissolving in 2-<br />

methoxyethanol [CH3OCH2CH2OH] solvent. In order to measure electrical properties, Pt top<br />

electrodes were deposited using e-beam evaporator. Structural properties <strong>of</strong> PZT thin films<br />

were characterized using x-ray diffraction technique. In this presentation, we will discuss the<br />

photovoltaic properties <strong>of</strong> PZT thin film capacitors in a function <strong>of</strong> Zr/Ti ratio.<br />

P- 20


<strong>Poster</strong> session I<br />

Effects <strong>of</strong> Concentration <strong>of</strong> Multi-walled Carbon Nanotube (MWCNT) on<br />

Electrical Properties <strong>of</strong> MWCNT�Pb(Zr0.52Ti0.48)O3 Composite Films<br />

Jin Kyu Han, Jin Ho Kwak and Sang Don Bu *<br />

Department <strong>of</strong> Physics, Chonbuk National <strong>University</strong>, Jeonju 561-756, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: sbu@chonbuk.ac.kr<br />

Conductive fillers such as multi-walled carbon nanotubes (MWCNTs) have attracted<br />

extensive attention for their electrical properties. The incorporation <strong>of</strong> the fillers into oxide<br />

materials provides available opportunities for attaining composite with high dielectric<br />

constant, conductivity. According to the literature, the incorporation <strong>of</strong> MWCNT in<br />

ferroelectric thin film can lead to an improvement <strong>of</strong> the electron mobility and interface<br />

polarization between the MWCNT and the films. They can result in promoted dielectric<br />

constant <strong>of</strong> the film.<br />

We report the effects <strong>of</strong> concentration <strong>of</strong> the MWCNT on the electrical properties <strong>of</strong><br />

Pb(Zr0.52Ti0.48)O3 (PZT) in a film structure. The MWCNT�PZT films were prepared by using<br />

a sol-gel process, spin-coating method, and rapid thermal annealing process. The MWCNT is<br />

purified using a heat and an acid treatment to remove metal impurities and simultaneously to<br />

enhance the dispersion <strong>of</strong> MWCNT in the solution. The purified MWCNT bundles were<br />

mixed with PZT sol-gel solution <strong>of</strong> 1 wt% to 30 wt% concentration by a ultrasonic dispersion<br />

method. The MWCNT�PZT solution was deposited onto (111) Pt/Ti/SiO2/Si substrates by<br />

spin-coating with 3000 rpm for 60 s and then they were pyrolyzed. They are annealed at high<br />

temperatures <strong>of</strong> 500�700 o C in a nitrogen atmosphere. The morphological, structural,<br />

electrical properties <strong>of</strong> MWCNT�PZT composite films are studied with field-emission<br />

scanning electron microscope, x-ray diffraction, TF Analyzer and HP 4194A impedance<br />

analyzer. The variation <strong>of</strong> electron mobility and dielectric constant with the increase <strong>of</strong><br />

MWCNT in MWCNT-PZT composite films will be discussed.<br />

P- 21


<strong>Poster</strong> session I<br />

Structure and electrical properties <strong>of</strong> Ba(Zrx,Ti1-x)O3 thin films by reactive<br />

sputtering method using metallic target<br />

J.W. Kim 1 , H. Funakubo 2* , H. Shima 1 , K. Nishida 1 and T. Yamamoto 1<br />

1 Dept. <strong>of</strong> communications Eng., National Defense Academy, Kanagawa 239-8686, Japan<br />

2* Dept. <strong>of</strong> Engineered Materials, Tokyo Institute <strong>of</strong> Tech., Kanagawa 226-8503, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : em50059@nda.ac.jp<br />

Barium Titanate (BaTiO3) and perovskite materials are typical ferroeletric material<br />

which have been widely used for various electronic devices. Especially, Ba(Zrx,Ti1-x)O3(BZT)<br />

has been chosen in the fabrications <strong>of</strong> ceramic capacitors because Zr 4+ is chemically more<br />

stable than Ti 4+ 1) . Moreover, it is reported that the increase in the Zr content decrease grain<br />

size and dielectric constant 2) . Recently, since the size <strong>of</strong> electronic devices are decreased,<br />

application <strong>of</strong> film form is extensively investigated. BZT thin films were generally obtained<br />

by sputtering method using ceramics target. But it is difficult to control the composition <strong>of</strong> the<br />

films in case <strong>of</strong> ceramics target. Then, we applied the reactive sputtering method for preparing<br />

BZT thin films using a metal target. The BZT thin film can be easily controlled by changing<br />

the Ba, Zr and Ti metal target area ratio. In this study, BZT thin films were grown by<br />

sputtering system using metal target and their characteristics were investigated.<br />

The BZT thin films were deposited on (100)MgO and (100)Pt/(100)MgO substrate by a<br />

RF magnetron reactive sputtering method using metal targets. XRD and XRF was carried out<br />

to investigate the crystallinity and composition <strong>of</strong> BZT thin films. The surface morphology<br />

and domain structure <strong>of</strong> the BZT thin films were investigated with AFM and PFM. The<br />

electrical properties <strong>of</strong> the BZT thin films were measured by ferroelectric test system.<br />

Figure 1 shows P-E hysteresis loops for BZT films<br />

80<br />

with different Zr contents and schematic drawing <strong>of</strong> metal<br />

60<br />

Zr = 0%<br />

target. It was possible to control the films by changing the<br />

40<br />

20<br />

Zr = 30%<br />

metal targets area ratio. Moreover, it was found that all the<br />

0<br />

Zr = 40%<br />

films were only (001)/(100) orientated and the ratio <strong>of</strong> -20<br />

Ba/Ti was stoichiometry. It reveals that high quality BZT<br />

-40<br />

-60<br />

films were obtained with different Zr contents using metal<br />

target. We are going to discuss about the results <strong>of</strong> surface<br />

-80<br />

morphology, electrical properties and these characteristic<br />

Electric field (kV/cm)<br />

Fig. 1. P-E hysteresis loops for BZT films<br />

<strong>of</strong> other BZT thin films on various substrates.<br />

with different Zr contents<br />

References :<br />

1) B.L. Cheng et al., J. Eur. Ceram. Soc. 25 (2005) 2295–2298.<br />

2) J.W. Zhai et al., Appl. Phys. Lett. 84 (2004) 3136–3138.<br />

P- 22<br />

Polarization(�C/cm 2 )<br />

-3000 -2000 -1000 0 1000 2000 3000


<strong>Poster</strong> session I<br />

Fabrication <strong>of</strong> Orientated (Na0.5K0.5)NbO3-BaZrO3-(Bi0.5Li0.5)TiO3 Thin<br />

Films on LaNiO3/SiO2/Si Substrates by Pulsed Laser Deposition<br />

T. Nakao 1,* , M. Fukada 1 , S. Yamazoe 1,2 , T. Wada 1, K. Komaki 3 and H. Adachi 3<br />

1 Department <strong>of</strong> Materials Chemistry, Ryukoku <strong>University</strong>, Japan<br />

2 Department <strong>of</strong> Chemistry, School <strong>of</strong> Science, The <strong>University</strong> <strong>of</strong> Tokyo, Japan<br />

3 Panasonic Corporation, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : t12m082@mail.ryukoku.ac.jp<br />

Wang et al. reported that 0.92(Na0.5K0.5)NbO3-0.06BaZrO3-0.02(Bi0.5Li0.5)TiO3 (NKN-<br />

BZ-BLT) ceramics showed a large d33 <strong>of</strong> 420 pC/N. We successfully fabricated NKN-BZ-<br />

BLT thin films on Pt/(001)MgO [1] and (100)Pt/Ti/SiO2/(111)Si substrates [2] by pulsed laser<br />

deposition (PLD). In this study, we fabricated NKN-BZ-BLT thin film on Si substrate with an<br />

LaNiO3 (LNO) layer as a bottom electrode.<br />

We deposited NKN-BZ-BLT films in the following conditions: laser repetition rate 10<br />

Hz, O2 partial pressure about 225 mTorr, substrate temperature 800°C, and 300,000 laser<br />

shots. The crystalline structures <strong>of</strong> the films were measured by �/2� X-ray diffraction analysis.<br />

The P-E hysteresis loops were observed using a ferroelectric tester. Figures 1 shows X-ray<br />

diffraction patterns <strong>of</strong> (a) LNO/SiO2/Si substrate, (b) NKN-BZ-BLT film on LNO/SiO2/Si<br />

and (c) NKN-BZ-BLT film on (111)Pt/Ti/SiO2/(100)Si substrates. In Fig. 1 (a), we observe<br />

100 and 200 LNO peaks at 23.3 and 47.5 o , respectively. The LNO layer has a 100 preferred<br />

orientation. In Fig. 1 (b), we observe strong 100 and 200 NKN-BZ-BLT peaks at around 22.6<br />

and 45.9 o , respectively. This NKN-BZ-BLT film has (100) preferred orientation. The pseudotetragonal<br />

lattice constants <strong>of</strong> NKN-BZ-BLT (ap = 3.979Å and cp = 3.993Å) are larger than<br />

that <strong>of</strong> LNO (ap = 3.842Å as pseudo-cubic). In Fig. 1 (c), we can observe a 110 NKN-BZ-<br />

BLT peak as well as 100 and 200 peaks. Figure 2 shows the P-E hysteresis <strong>of</strong> NKN-BZ-BLT<br />

thin films fabricated on LNO/SiO2/(100)Si substrate. This film showed ferroelectric behavior,<br />

and remanent polarization Pr is 1.8 �C/cm 2 .<br />

[1] S. Yamazoe et al., Jpn. J. Appl. Phys., 49, 09MA06 (2010), ibid, 50, 09N<br />

Intensity (cps) Intensity (cps) Intensity (cps)<br />

10 6 10 0<br />

10 1<br />

10 2<br />

10 3<br />

10 4 10 0<br />

10 1<br />

10 2<br />

10 3<br />

10 4<br />

10 4<br />

10 2<br />

100 NKN-<br />

BZ-BLT<br />

100 NKN-<br />

BZ-BLT<br />

100 LNO<br />

110 NKN-<br />

BZ-BLT<br />

200 NKN-<br />

BZ-BLT<br />

(b)<br />

10 0<br />

10 15 20 25 30 35 40 45 50 55 60<br />

2� (degrees)<br />

Fig. 1 X-ray diffraction patterns <strong>of</strong> (a) LaNiO3(LNO)<br />

/SiO2/Si substrate and (b) NKN-BZ-BLT film on<br />

LNO/SiO2/Si and (c) NKN-BZ-BLT film on<br />

(111)Pt/Ti/SiO2/(100)Si substrates.<br />

111 Pt<br />

SiO 2<br />

200 LNO<br />

200 NKN-<br />

BZ-BLT<br />

(a)<br />

(c)<br />

P- 23<br />

Polarization / �C cm -2<br />

5<br />

4<br />

3<br />

2<br />

1<br />

0<br />

-1<br />

-2<br />

-3<br />

-4<br />

-5<br />

-400 -200 0 200 400<br />

Applied electric field / kV cm -1<br />

Fig. 2 P-E hysteresis loop <strong>of</strong> NKN-BZ-BLT film<br />

fabricated on LaNiO3(LNO)/SiO2/Si substrate.


<strong>Poster</strong> session I<br />

(Ag,Li)NbO3 thin films fabricated on (001), (110), and (111)SrTiO3<br />

substrates by pulsed laser deposition<br />

Yu Yamamoto 1 *, Seiji Yamazoe 1,2 and Takahiro Wada 1<br />

1 Department <strong>of</strong> Materials Chemistry, Ryukoku <strong>University</strong>, Japan<br />

2 Department <strong>of</strong> Chemistry, School <strong>of</strong> Science, The <strong>University</strong> <strong>of</strong> Tokyo, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : t12m093@mail.ryukoku.ac.jp<br />

AgNbO3 (AN) has attracted attention as a lead-free material. We have successfully<br />

fabricated AN films on (001), (110), and (111)SrTiO3 (STO) substrates by pulsed laser<br />

deposition (PLD) [1]. The films showed different dielectric and ferroelectric properties<br />

depending on crystal orientation <strong>of</strong> STO substrates. In this work, we fabricated (Ag1xLix)NbO3<br />

(ALN) thin films with x= 0.05 and 0.10 on (001), (110), and (111)STO substrates<br />

by PLD.<br />

Before deposition <strong>of</strong> the ALN film, we deposited SrRuO3 (SRO) film as a bottom<br />

electrode on (001), (110), and (111) STO substrates. Then, we deposited ALN films with a<br />

thickness <strong>of</strong> 2~4 �m. The fabrication conditions were as follows: laser repetition rate 10 Hz,<br />

target and substrate distance 90 mm, O2 partial pressure about 225 mTorr, substrate<br />

temperature <strong>of</strong> 700°C, and 750,000 laser shots. The crystalline structures <strong>of</strong> the ALN films<br />

were measured by θ/2θ X-ray diffraction analysis. To characterize the surface morphologies,<br />

the surfaces were observed by SEM. The relative dielectric constant εr and dielectric loss tanδ<br />

were measured by an LCR meter, and P-E hysteresis loops were observed using a<br />

ferroelectric tester.<br />

X-ray diffraction (XRD) showed that ALN(x=0.05, 0.10) films were epitaxially grown<br />

on (001), (110), (111) STO substrates. The diffraction peaks <strong>of</strong> the ALN films shifted to<br />

higher angle with increasing Li concentration, x. Figures 1 show SEM surface micrographs <strong>of</strong><br />

the ALN films deposited on (001), (110), and (111) STO substrates. The figures clearly show<br />

that the surface textures <strong>of</strong> the ALN films are different by the crystal orientation <strong>of</strong> the STO<br />

substrate. The ALN film on (001)STO has a smooth surface with several square holes. The<br />

film on (110)STO has a striped pattern, and that on (111)STO has a trigonal pyramid-like<br />

structures. We reported similar microstructures for AN [1] and NaNbO3 [2] films fabricated<br />

on the (001), (110), and (111) STO. The P-E hysteresis showed that the ALN(x=0.1) film on<br />

(111) STO exhibited a ferroelectric behavior and had the largest remanent polarization (Pr) <strong>of</strong><br />

40 �C/cm 2 <strong>of</strong> all the ALN films.<br />

[1] H. Sakurai, S. Yamazoe, and T. Wada, Appl. Phys. Lett. 97, 042901 (2010).<br />

[2] S. Yamazoe et. al., Appl. Phys. Lett. 95, 062906 (2009).<br />

(001)SrTiO3 (110)SrTiO3 (111)SrTiO3<br />

Fig. 1 Surface SEM micrographs <strong>of</strong> (Ag0.9Li0.1)NbO3 thin films deposited on (001), (110) and (111) SrTiO3<br />

substrates.<br />

P- 24


<strong>Poster</strong> session I<br />

The effect <strong>of</strong> crystallization process <strong>of</strong> P(VDF/TrFE) thin film on<br />

the ferroelectric properties<br />

Yoshiki Yachi, Takeshi Yoshimura, Atsushi Ashida and Norifumi Fujimura<br />

Graduate School <strong>of</strong> Engineering, Osaka Prefecture <strong>University</strong><br />

1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : tyoshi@pe.osakafu-u.ac.jp<br />

Poly(vinylidene fluoride/trifluoroetylene)[P(VDF/TrFE)] has attracted a great deal <strong>of</strong><br />

attention in recent years due to the potential for device applications such as micro sensors and<br />

actuators. P(VDF/TrFE) have a Curie temperature (Tc) between 100-130℃, which depends<br />

on the composition. 1 For P(VDF/TrFE) thin films, annealing treatment is usually employed<br />

for the crystalization 2 . In this study, P(VDF/TrFE) films are prepared at different annealing<br />

temperatures and the relationship between the structure and ferroelectric properties is<br />

investigated.<br />

P(VDF/TrFE) with a composition 75/25 mol% was deposited by a spin cast method on<br />

Pt/Ti/SiO2/Si substrates. Methyl ethyl ketone was used for the solvent. The films were<br />

annealed between 40 and 140 o C. Al top electrodes were deposited on the films. The<br />

crystallization <strong>of</strong> the films was investigated by X-ray diffraction (XRD). Fig. 1 shows the<br />

annealing temperature dependence <strong>of</strong> the XRD integral intensity <strong>of</strong> the (200), (110)<br />

diffraction and the remnant polarization (Pr). The results indicate that the films crystalize by<br />

the annealing above 100 o C. On the other hand, Pr increases at the annealing temperature <strong>of</strong><br />

130~140 o C (above the Tc). Thus the annealing temperature to improve the ferroelectric<br />

properties is different from the crystallization temperature. It is suggested that the increase <strong>of</strong><br />

Pr is caused by the annealing above the Tc. In parraelectric phase, molecular chain rotates<br />

around the chain axis and is quite mobile along it. 2 Therefore, it can be expected that the<br />

annealing in the paraelectric phase enhances<br />

the realignment <strong>of</strong> the molecular chain,<br />

which leads to the improvement <strong>of</strong> the<br />

ferroelectric properties <strong>of</strong> P(VDF/TrFE).<br />

Reference<br />

Fig.1 Annealing temperature dependence <strong>of</strong><br />

XRD integral intensity (triangle) and Pr<br />

(square)<br />

P- 25<br />

1 T. Furukawa, Phase Trans. 18, 143 (1989).<br />

2 H. Ohigashi et al., Appl. Phys. Lett. 66, 1079<br />

(1995).


<strong>Poster</strong> session I<br />

Effects <strong>of</strong> La substitution for BiFeO3 epitaxial thin films<br />

K. Wakazono, Y. Kawahara, K. Ujimoto, T. Yoshimura and N. Fujimura<br />

Graduate School <strong>of</strong> Engineering, Osaka Prefecture <strong>University</strong><br />

1-1 Gakuen-cho, Nakaku, Sakai, Osaka,599-8531, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : tyoshi@pe.osakafu-u.ac.jp<br />

Recently, BiFeO3 (BFO) thin films have been attracted great interest 1 , because BFO is<br />

Pb-free ferroelectric and has large spontaneous polarization (~100 �C/cm 2 ). We have reported<br />

that the direct piezoelectric properties <strong>of</strong> BFO thin films are comparable to that <strong>of</strong> PZT thin<br />

films. For the Pb-based ferroelectrics, it is known that the piezoelectric properties increase<br />

with decreasing the Curie temperature. In this study, we fabricated BFO and (Bi0.9, La0.1)FeO3<br />

(BLFO) epitaxial thin films and discuss the effect <strong>of</strong> La substitution on crystallographic and<br />

electrical properties, because La substitution decreases the Curie temperature.2<br />

BLFO and BFO thin films were grown at 590, 620, 650 ºC and 580, 620, 660 ºC,<br />

respectively, using pulsed laser deposition system on (001) SrRuO3/(001) SrTiO3, the<br />

thickness is about 50 nm. Figure 1 shows the surface morphology <strong>of</strong> BLFO and BFO thin<br />

films observed by atomic force microscopy. As can be seen, BLFO thin films have smooth<br />

surface than BFO thin films and have less dependence on the deposition temperature. The<br />

crystal structure <strong>of</strong> the films was investigated by X-ray diffraction 2��� scan and rocking<br />

curve measurement. As shown in Fig.2, BLFO thin films have smaller full width at half<br />

maximum (FWHM) <strong>of</strong> (003) diffraction peak on the 2��� scan than BFO. Thus, the<br />

crystallinity <strong>of</strong> the BFO films is improved by La substitution on the A site.<br />

Reference<br />

[1]K.Ujimotoet al.,Appl. Phys. Lett., 100, 102901 (2012)<br />

[2]H.Uchida et al.,J.Appl.Phys.,100,014106 (2006)<br />

Fig. 1 Surface Morphology <strong>of</strong> BFO thin films deposited at<br />

(a)580 ºC,(b)620 ºC,(c)660 ºC and BLFO thin films<br />

deposited at (d)590 ºC,(e)620 ºC,(f)650 ºC<br />

P- 26<br />

Fig. 2 FWHM <strong>of</strong> XRD 2��� scan and<br />

rocking curve <strong>of</strong> (003) diffraction.


<strong>Poster</strong> session I<br />

Phase transition behaviors in La-doped Bi1/2(Na0.82K0.18)1/2TiO3 lead-free<br />

piezoelectric ceramics<br />

Thi Hinh Dinh 1 , Hyoung-Su Han 1 , Van Quyet Nguyen 1 , Dae-Jun Heo 1 ,<br />

Chang Won Ahn 2 and Jae-Shin Lee 1*<br />

1 School <strong>of</strong> Materials Science and Engineering, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong>, Korea<br />

2 Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong>, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: jslee@ulsan.ac.kr<br />

This study investigated the phase transition, dielectric, and electromechanical properties<br />

<strong>of</strong> A-site donor doped [Bi1/2(Na0.82K0.18)1/2]TiO3 (BNKT) ceramics, in which La was selected<br />

as the A-site donor. The bismuth-based perovskite [Bi1/2(Na0.82K0.18)1/2]1-xLaxTiO3 (La100x; x<br />

= 0.00-0.05) were successfully fabricated by conventional solid state method. The effects <strong>of</strong><br />

poling process on the crystal structural and dielectric properties <strong>of</strong> the ceramics were analyzed.<br />

A systematic X-ray diffraction study <strong>of</strong> poled and unpoled specimens revealed significant<br />

differences in unit cell parameters between them. As the La-doping level increased from 0 to<br />

5 mol%, there happened a phase transition from the coexistence <strong>of</strong> rhombohedral and<br />

tetragonal phases to a pseudocubic symmetry at x=0.03 for unpoled specimens and at x =0.04<br />

for poled specimens, respectively.<br />

From measurements <strong>of</strong> temperature dependent dielectric properties, all specimens<br />

showed strong frequency dependent dispersions, which is a symptom <strong>of</strong> relaxor ferroelectrics.<br />

Although the maximum dielectric constant reached at about 280 o C, a hump at lower<br />

temperature was found for all specimens, which was formerly known as the depolarization<br />

temperature (Td). The Td shifted down as the La-doping level increased. Interesting was that a<br />

large electric-field-induced strain was observed when the La content reached 3 mol% as<br />

reported in previous studied on B-site donor doped BNKT ceramics. This presentation will<br />

discuss the nature and electrical properties <strong>of</strong> phases observed in La-doped BNKT ceramics.<br />

P- 27


<strong>Poster</strong> session I<br />

Low Frequency Dielectric Dispersion and Conduction Behaviors <strong>of</strong> BaTiO3<br />

modified Na0.5Bi0.5TiO3 Ferroelectric Ceramics<br />

J. S. Kim 1* , A. Hussain 1 , G. H. Ryu 1 , M. H. Kim 1 , T. K. Song 1 and W. J. Kim 2<br />

1 School <strong>of</strong> Nano & Advanced Materials Engineering, Changwon National<br />

<strong>University</strong>, Gyeongnam 641-773, Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Gyeongnam 641-773,<br />

Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimjjin@changwon.ac.kr<br />

The ferroelectric and electrical properties <strong>of</strong> Bi0.5Na0.5TiO3 (BNT) based ceramics have<br />

been extensively investigated. However, limited attention has been paid to ion doping effect<br />

<strong>of</strong> these materials. To investigate the effect <strong>of</strong> ion doping on dielectric and ferroelectric<br />

behaviors <strong>of</strong> lead free Bi0.5Na0.5TiO3 based ferroelectric ceramics, we prepared BaTiO3<br />

modified Bi0.5Na0.5TiO3 (BNT:BT) ceramics by a solid-state reaction method. The crystallized<br />

phase and grain morphology <strong>of</strong> the BNT:BT ceramics were confirmed by X-ray diffraction<br />

and scanning electron microscopy (SEM) studies, respectively. The BaTiO3 doping<br />

influenced the structural phase transition, dielectric properties and ferroelectric behaviors.<br />

With increasing BaTiO3 doping, the phase transition temperature (TR-T, i.e phase transition<br />

from the rhombohedral to the tetragonal symmetry) shifted to low temperature and the<br />

dielectric peak was broad. On the other hand, the dielectric peak depended on the measuring<br />

frequency and shifted to the higher temperature, which indicates a ferroelectric relaxor likebehavior.<br />

The substitution <strong>of</strong> BaTiO3 affects the degree <strong>of</strong> disorder in crystallographic A sites<br />

in (A,B)O3 perovskite structure. In addition, we studied the effects <strong>of</strong> ion doping on<br />

ferroelectric, dielectric dispersion and conduction behaviors in detail.<br />

P- 28


<strong>Poster</strong> session I<br />

Low Frequency Optical Phonons in SrTiO3 under Uniaxial Stress<br />

Yuhji Tsujimi * and Tomori Yanagisawa<br />

Research Institute for Electronic Science, Hokkaido <strong>University</strong>, Sapporo 001-0020, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : yts@es.hokudai.ac.jp<br />

Strontium titanate SrTiO3 is known to have the quantum paraelectric state (QPS) below<br />

about Tq = 37 K.[1] It has been reported from Raman scattering and SHG experiments that the<br />

transition from the QPS to the quantum ferroelectric state (QFS) is caused by the application<br />

<strong>of</strong> uniaxial stress.[2, 3] In order to understand the dynamical mechanism <strong>of</strong> the transition, we<br />

have performed the 180 o light scattering experiment with a scattering vector <strong>of</strong> q // [001]c and<br />

observed the ferroelectric Eu(x, y) s<strong>of</strong>t mode (FE mode) under the uniaxial stress ���along the<br />

[010]c direction). The size <strong>of</strong> the sample was 2.0[100]c �1.65 [010]c�4.1[001]c mm 3 .<br />

Figure shows the frequency shift (��: left panels) and line width (��: right panels) <strong>of</strong> the<br />

FE mode as a function <strong>of</strong> �. Upper, middle and lower panels correspond to the experimental<br />

results obtained at T = 5.0, 10.3, and 16.5 K, respectively. Yamanaka et al. measured ��<br />

(only) under the atmospheric pressure by using a Hyper Raman scattering method.[4] Their<br />

results are presented in the figure by symbols ( ). Combining their results and ours, we can<br />

state that the FE mode does not s<strong>of</strong>ten completely even at critical stresses � c (7±1, 8±1, and<br />

13±1 kg/mm 2 at T = 5.0, 10.3, and 16.5 K, respectively). Moreover, �� clearly increases near<br />

� c. Especially, �� takes the maximum value at around � c at T = 16.5 K. Basing on these<br />

results, we discuss the similarities between the QPS-QFS transition <strong>of</strong> SrTiO3 and that <strong>of</strong><br />

SrTi 18 O3.<br />

We also present our finding that the intensity <strong>of</strong> the spectral peak (which is characteristic<br />

<strong>of</strong> the QPS and is called “broad doublet”<br />

(BD) [5]) drastically increases near � c<br />

~13±1 at T = 16.5 K. This fact clearly<br />

indicates that the BD must be the mode<br />

related with the critical phenomena.<br />

[1] K.A.Müller and H.Burkard, PRB 19<br />

(1979) 3593. [2] H.Uwe and T.Sakudo;<br />

PRB 13 (1976) 271. [3] Y.Fujii et al.;<br />

JPSJ 56 (1987) 1940. [4] A.Yamanaka et<br />

al.: Europhys. lett. 50 (2000) 688. [5]<br />

B.Hehlen et. al.; PRL 75 (1995) 2416.<br />

P- 29


<strong>Poster</strong> session I<br />

Temperature-Field Phase Diagrams in Pb(Zn1/3Nb2/3)O3-8%PbTiO3<br />

Makoto Iwata 1* , Sadaharu Kato 1 , Kazuki Tanaka 1 , Masaki Maeda 1<br />

and Yoshihiro Ishibashi 2<br />

1 Graduate School <strong>of</strong> Engineering, Nagoya Institute <strong>of</strong> Technology, Nagoya 466-8555, Japan<br />

2 Department <strong>of</strong> Applied Physics, Nagoya <strong>University</strong>, Nagoya 464-8603, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : miwata@nitech.ac.jp<br />

It is known that solid solution <strong>of</strong> 92%Pb(Zn1/3Nb2/3)O3-8%PbTiO3 (PZN-8%PT) near the<br />

morphotropic phase boundary (MPB) show giant dielectric and piezoelectric responses. It was<br />

claimed that such giant responses essentially come from the transversal instability near MPB<br />

on the basis <strong>of</strong> the Landau-type free energy, where the dielectric constant perpendicular to the<br />

spontaneous polarization becomes extremely large because anisotropy <strong>of</strong> the free energy in<br />

the parameter space becomes small. 1)<br />

It was reported that the critical end point (CEP) appears under the DC electric field in a<br />

related material Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-xPT), and was pointed out that the giant<br />

electromechanical response in PMN-xPT is the manifestation <strong>of</strong> CEP in addition to the<br />

physical property <strong>of</strong> MPB. 2) On the basis <strong>of</strong> the Landau-type free energy function, anisotropy<br />

<strong>of</strong> dielectric properties and temperature-field phase diagrams were qualitatively explained. 3)<br />

In our previous study, we reported our experimental results <strong>of</strong> the DC field dependence <strong>of</strong> the<br />

dielectric constant as a function <strong>of</strong> temperature in the [001]-direction <strong>of</strong> PZN-8%PT, and<br />

clarify the temperature-field phase diagram. 4-6)<br />

In the present study, we have investigated the DC field dependence <strong>of</strong> the dielectric<br />

constant as a function <strong>of</strong> temperature in the (001)-, (011)-, and (111)-plates <strong>of</strong> PZN-9%PT.<br />

The temperature-field phase diagrams along these directions have been clarified. It has been<br />

found that the tetragonal phase disappears under the electric field above 10 kV/cm along<br />

[011]- or [111]-direction. It is pointed out that, on approaching CEP, both the energy cost and<br />

the electric field required to induce the rotation <strong>of</strong> the spontaneous polarization remarkably<br />

decrease. This will explain the giant electromechanical response in PZN-xPT as Kutnjak et al.<br />

proposed. 2) Nature <strong>of</strong> the phase transition based on our experimental results has been also<br />

discussed.<br />

1. Y. Ishibashi and M. Iwata: Jpn. J. Appl. Phys. 37 (1998) L985.<br />

2. Z. Kutnjak, J. Petzelt, and Blinc: Nature 441 (2006) 956.<br />

3. M. Iwata, Z. Kutnjak, Y. Ishibashi and R. Blinc: J. Phys. Soc. Jpn. 77 (2008) 034703.<br />

4. M. Iwata, K. Sakakibara, R. Aoyagi, M. Maeda, and Y. Ishibashi: Ferroelectrics 405<br />

(2010) 39.<br />

5. M. Iwata and Y. Ishibashi: Phase Transitions 84 (2011) 753.<br />

6. M. Iwata, S. Kato, and Y. Ishibashi: Ferroelectrics 415 (2011) 20.<br />

P- 30


<strong>Poster</strong> session I<br />

Charge density study <strong>of</strong> BiFeO3-PbTiO3 solid solution system with large<br />

tetragonal lattice distortion<br />

Kazuaki Taji 1* , Chikako Moriyoshi 1 , Yoshihiro Kuroiwa 1 , Hiroki Moriwake 2 ,<br />

Shuvrajyoti Bhattacharjee 3 and Dhananjai Pandey 3<br />

1 Department <strong>of</strong> Physical Science, Hiroshima <strong>University</strong>, Hiroshima 739-8526, Japan<br />

2 Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8526, Japan<br />

3 School <strong>of</strong> Material Science and Tech., Banaras Hindu <strong>University</strong>, Varanasi-221005, India<br />

* E-mail address <strong>of</strong> the corresponding author : tajikazuaki@hiroshima-u.ac.jp<br />

The solid solution system (1-x)BiFeO3-xPbTiO3 (BF-xPT) has attracted wide attention<br />

due to the multiferroic properties. Recently we have found that the tetragonal-tetragonal<br />

isostructural phase transition takes place near the morphotropic phase boundary (MPB) in BFxPT<br />

[1]. For example, BF-0.31PT with large tetragonal lattice distortion c/a = 1.187 at RT<br />

undergoes the phase transition to the cubic phase at high temperature through the other<br />

isostructural tetragonal phase with less tetragonal lattice distortion. The curious phase<br />

transition is originated from the extraordinarily large lattice distortion which cannot be<br />

observed other perovskite-type solid solutions such as PZT and PMN-PT. In this study, we<br />

have carried out the crystal structure analysis at the charge density levels in BF-xPT system to<br />

reveal the origin <strong>of</strong> the large tetragonal lattice distortion by analyzing synchrotron radiation<br />

powder diffraction data measured at SPring-8 BL02B2 using the MEM/Rietveld method.<br />

We have found that the large tetragonality <strong>of</strong> this system is characterized by shortening<br />

<strong>of</strong> Bi/Pb-O bonding, elongation <strong>of</strong> Fe/Ti-O bonding, and decreasing <strong>of</strong> O-Fe/Ti-O angle with<br />

decreasing composition x in the tetragonal phase. The other bond lengths are nearly constant.<br />

The characteristic chemical bondings, that are Fe/Ti in 5-fold O coordination and covalent<br />

Bi/Pb-O bonding, are clearly visualized in the MEM charge density map in the entire<br />

tetragonal composition range x > 0.31 at RT. In BF-0.31PT, significantly higher bonding<br />

electron density is observed on the Bi/Pb-O and Fe/Ti-O bonds. The oxygen polyhedron can<br />

be regarded as an Fe/Ti-O5 pyramid rather than an Fe/Ti-O6 octahedron. Hence, we consider<br />

that the large tetragonal lattice distortion in BF-xPT solid solution system is originated from<br />

the doping effect <strong>of</strong> the Bi ion to form the Bi-O electron orbital hybridization which involves<br />

a layered structure in the tetragonal phase at RT.<br />

[1] S. Bhattacharjee, K. Taji, C. Moriyoshi, Y. Kuroiwa, and D. Pandey, Phys. Rev. B 84,<br />

104116 (2011).<br />

P- 31


<strong>Poster</strong> session I<br />

Electric-field-induced phase transition <strong>of</strong> BaTiO3-based ceramics<br />

Mayuko Ogawa 1* , Chikako Moriyoshi 1 ,Yoshihiro Kuroiwa 1 ,<br />

Noriyuki Inoue 2 and Takafumi Okamoto 2<br />

1 Department <strong>of</strong> Physical Science, Hiroshima <strong>University</strong>, Kagamiyama, Higashi-Hiroshima,<br />

Hiroshima 739-8526, Japan<br />

2 Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto 617-8555, Japan<br />

* E-mail address<strong>of</strong> the corresponding author:mayuko-ogawa@sci.hiroshima-u.ac.jp<br />

BaTiO3, one <strong>of</strong> perovskite-type ferroelectrics, is applied to multilayer ceramic capacitors<br />

(MLCCs) as a dielectric material. To satisfy requirements for the lower dielectric loss and<br />

lower microphonics, rare-earth Rand Mg ions co-substituted BaTiO3 ceramics are proposed as<br />

candidates for the dielectrics. This co-substitution enables us to suppress various problems<br />

involved in applying the dielectric properties <strong>of</strong> pure BaTiO3 to MLCCs. Gd and Mg cosubstituted<br />

(Ba0.94Gd0.06)(Ti0.97Mg0.03)O3 (BGTM) is a promising material in respect <strong>of</strong><br />

suppressing the insulation degradation[1]. The aim <strong>of</strong> our study is to clarify the relationship<br />

between the electric polarization and crystal structure <strong>of</strong> BGTM in the environments realizing<br />

the electric device operating. In this paper, we demonstrate in situ lattice strain observation <strong>of</strong><br />

BGTM under variations <strong>of</strong> temperature and external electric field using a sample fabricated<br />

based on MLCC by synchrotron radiation diffraction.<br />

Powder diffraction patterns <strong>of</strong> BGTM were measured by the large Debye-Scherrer<br />

camera installed at BL02B2 in SPring-8. We used the high-energy X-rays <strong>of</strong> 35 keV (��= 0.35<br />

Å) to investigate the inside <strong>of</strong> the sample in the transmission geometry. The lattice strain <strong>of</strong><br />

BGTM was observed in the temperature range <strong>of</strong> T = 200–400 K and the electric-field range<br />

<strong>of</strong> E = 0 –300 kV/cm.<br />

The first order phase transition which involves a discontinuous change in the lattice<br />

strain was observed in BGTM at TC = 293 K, without applying electric field. When the<br />

electric field was applied just above TC, the electric-field-induced phase transition took place<br />

with an abrupt change in the lattice strain. The change turned out gradually when the electric<br />

field was applied far above TC. We propose the E-T phase diagram <strong>of</strong> BGTM with the critical<br />

point (Ecrit, Tcrit).<br />

[1] N. Inoue, T. Okamatsu, A. Ando, H. Takagi, T. Hashimoto, C. Moriyoshi, and Y.<br />

Kuroiwa: Jpn. J. Appl. Phys. 48, 09KF03 (2009).<br />

P- 32


<strong>Poster</strong> session I<br />

Structural characteristics <strong>of</strong> Ca-substituted BaTiO3 in cubic phase by high<br />

energy synchrotron radiation powder diffraction<br />

Shoichi Takeda 1* ,Chikako Moriyoshi 1 , Eisuke Magome 1 , Yoshihiro Kuroiwa 1<br />

and Jun Ikeda 2<br />

1 Graduate School <strong>of</strong> Science, Hiroshima<strong>University</strong>, Kagamiyama, Higashi-Hiroshima,<br />

Hiroshima 739-8526, Japan<br />

2 Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto 617-8555, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : shoichi-takeda@hiroshima-u.ac.jp<br />

In the Ca-substituted BaTiO3 system (Ba1-xCax)TiO3 (BCT), the phase transition<br />

temperatures show nonlinear variations with the Ca-composition x; the cubic-tetragonal phase<br />

transition temperature TC C-T is rather constant but which shows a relevant maximum TC C-T =<br />

407 K at x= 0.06, while both the tetragonal-orthorhombic and orthorhombic-rhombohedral<br />

phase transition temperatures, TC T-O and TC O-R , respectively decrease dramatically with<br />

increasing x, and the tetragonal phase is emerged as the most stable phase at low temperatures<br />

in the composition region <strong>of</strong> x > 0.23 [1], which makes a strong contrast with a linear<br />

variation <strong>of</strong> the lattice constant a in the cubic phase. The ferroelectric phase transitions in<br />

solid solutions can be closely connected with the structural characteristics and the<br />

ferroelectric instability caused in the prototype structure [2]. In this study, we analyzed the<br />

crystal structure <strong>of</strong> BCT in the cubic phase at the electron density levels to discuss the<br />

characteristics <strong>of</strong> the crystal structure which control the phase transitions in BCT.<br />

BCT sample powders (x = 0 – 0.20) were synthesized by a conventional solid state<br />

reaction method. Synchrotron radiation powder diffraction data were collected using the large<br />

Debye-Scherrer camera installed at SPring-8 BL02B2. The energy <strong>of</strong> X-rays was 30 keV<br />

(wave length λ= 0.41 Å). The crystal structure and electron charge density distribution was<br />

analyzed by the maximum entropy method (MEM)/Rietveld method. Subtle but clear<br />

tendency is observed in the electron charge density at the midpoint on the Ti-O bonding<br />

associated with the variation <strong>of</strong> TC C-T showing a maximum at x ~ 0.06. This result implies the<br />

validity <strong>of</strong> the orbital hybridization between Ti and O atoms controlling the TC C-T . We will<br />

discuss the change in TC T-O and TC O-R based on the thermal motions <strong>of</strong> the constituent atoms.<br />

[1] T. Mitsui and W.B. Westphal, Phys. Rev. 105, 1354(1961).<br />

[2] Y. Kuroiwa etal., Jpn. J. Appl. Phys. 44, 7151(2005).<br />

P- 33


<strong>Poster</strong> session I<br />

Nonpolar S<strong>of</strong>t Optic Phonon <strong>of</strong> Cubic-rhombohedral Phase Transition <strong>of</strong><br />

LaAlO3 Studied by Inelastic Light Scattering<br />

Yuto Fujita*, Kohei Suzuki, Tae Hyun Kim, and Seiji Kojima<br />

PAS,<strong>University</strong> <strong>of</strong> Tsukuba, Tsukuba, Ibaraki 305-8573, Japan<br />

*E-mail address <strong>of</strong> the corresponding author : yuto.fuji.4@gmail.com<br />

LaAlO3 undergoes an improper ferroelastic phase transition from the cubic phase (Pm3 _<br />

m) to nonpolar rhombohedral phase (R3 _<br />

c). The main structural difference between the cubic<br />

and rhombohedral phases is the rotation <strong>of</strong> AlO6 octahedra around one <strong>of</strong> the triad axes in the<br />

cubic phase [1]. Lattice instability <strong>of</strong> a cubic- rhombohedral phase transition is studied by<br />

low-frequency Raman scattering in the backward scattering geometry a(cc)a _<br />

using a double<br />

grating spectrometer (U1000) and a green YAG laser as an exciting source. The s<strong>of</strong>t optic<br />

mode in the paraelectric phase has F2u symmetry and is threefold degenerate. It splits into<br />

1A1g and 2Eg modes in the rhombohedral phase. These s<strong>of</strong>t modes are Raman active but<br />

infared inactive. The lowest Eg symmetry mode at 30 cm -1 shows remarkable s<strong>of</strong>tening<br />

toward the transition temperature Ttr=540℃ as shown in Fig.1. The elastic anomaly and<br />

central peak are also studied by broadband Brillouin scattering using a tandem-multipass<br />

Fabry-Perot interferometer [2].<br />

Intensity (arb.unit)<br />

3000<br />

2500<br />

2000<br />

1500<br />

1000<br />

500<br />

E g<br />

0<br />

-100 -80 -60 -40 -20 0 20 40 60 80 100<br />

Frequency shift (cm -1 )<br />

P- 34<br />

22 ℃<br />

150 ℃<br />

340 ℃<br />

500 ℃<br />

580 ℃<br />

Fig.1 Temperature dependence <strong>of</strong> Raman spectra <strong>of</strong> a LaAlO3 crystal.<br />

References<br />

1. S. A. Hayward et al., Phys. Rev. B 72 (2005) 054110.<br />

2. S. Kojima, Jpn. J. Appl. Phys. 49 (2010) 07HA01.<br />

A 1g


<strong>Poster</strong> session I<br />

Raman and Brillouin scattering studies on lead-free piezoelectric<br />

Bi0.5(Na0.78K0.22)0.5-xTiO3 ceramics with A-site vacancies<br />

Jae-Hyeon Ko 1* , Tae Hyun Kim 1,2 , Seiji Kojima 2 , Chang Won Ahn 3<br />

and Ill Won Kim 3<br />

1 Department <strong>of</strong> Physics, Hallym <strong>University</strong>, Gangwondo 200-702, Korea<br />

2 Graduate School <strong>of</strong> Pure and Applied Sciences, Univ. <strong>of</strong> Tsukuba, Ibaraki 305-8573, Japan<br />

3 Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : hwangko@hallym.ac.kr<br />

The acoustic and optic phonon properties<br />

<strong>of</strong> piezoelectric Bi0.5(Na0.78K0.22)0.5-xTiO3<br />

ceramics with A-site vacancies <strong>of</strong> x=0~0.05<br />

(BNKT-A) were investigated by using<br />

Brillouin and Raman spectroscopies at ambient<br />

temperature. These ceramics were located on<br />

the tetragonal side <strong>of</strong> the phase diagram close<br />

to the morphotropic phase boundary. The<br />

Brillouin spectrum consisted <strong>of</strong> a distributed<br />

longitudinal acoustic (LA) mode at ~ 50 GHz<br />

and a strong central peak. Since the ceramic<br />

samples were polycrystalline, the scattering<br />

events would occur at all scattering angles due<br />

to multiple refractions and reflections. The<br />

distributed Brillouin doublet <strong>of</strong> the LA mode<br />

became sharper appreciably when x was larger than<br />

0.015. This result was correlated with the fact that<br />

the density <strong>of</strong> BNKT-A became a maximum and<br />

was saturated for x ≥ 0.015. It is probable that the<br />

acoustic waves are not perturbed substantially at<br />

grain boundaries due to the high density and more<br />

compact sample condition at high x. Raman spectra<br />

<strong>of</strong> BNKT-A ceramics exhibited approximately<br />

seven broad peaks over the frequency range <strong>of</strong> 50 ~<br />

1000 cm -1 , consistent with previous Raman studies<br />

on similar lead-free ceramics. The peak positions<br />

were not sensitive to the concentration <strong>of</strong> A-site vacancies. The number <strong>of</strong> peaks was reduced<br />

in the paraelectric phase <strong>of</strong> BNKT-A.<br />

* This research was supported in part by Basic Science Research Program through the<br />

National Research Foundation <strong>of</strong> Korea (NRF) funded by the Ministry <strong>of</strong> Education, Science<br />

and Technology (2010-0010497).<br />

P- 35<br />

Intensity (arb. units)<br />

1500<br />

1000<br />

500<br />

Brillouin<br />

x=0<br />

x=0.005<br />

x=0.01<br />

x=0.015<br />

x=0.02<br />

x=0.03<br />

x=0.04<br />

x=0.05<br />

-60 -40 -20 0 20 40 60<br />

Frequency Shift (GHz)<br />

Raman


<strong>Poster</strong> session I<br />

Electric and Dielectric Properties <strong>of</strong> reduced La0.01Ba0.99TiO3<br />

Ahmed I. Ali 1,2 , Abdel Moez 3 and Yong Soo Kim 2*<br />

1 Basic Science Dep., Faculty <strong>of</strong> Industrial Education, Helwan <strong>University</strong>, Saray El-Quba,<br />

11281 Cairo, Egypt<br />

2 Dep. <strong>of</strong> Physics and Energy Harvest-Storage Research Center, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, 680-749<br />

<strong>Ulsan</strong>, Korea<br />

3 Solid State Physics Dep., Physical Research Division, National Research Center (NRC),<br />

Dokki, Cairo, Egypt.<br />

* E-mail address <strong>of</strong> the corresponding author: yskim2@ulsan.ac.kr<br />

The technological application <strong>of</strong> BaTiO3 system has been attracted a great deal <strong>of</strong><br />

attention due to its excellent dielectric properties, such as low dielectric loss and low<br />

temperature coefficients <strong>of</strong> dielectric constants. In this report, the electrical properties -<br />

resistivity and carrier concentration- <strong>of</strong> reduced La0.01Ba0.99TiO3 were investigated<br />

experimentally in the temperature range (300 K ~ 600 K). The samples were reduced at<br />

1380 °C under around 10 -14 atmosphere <strong>of</strong> oxygen pressure. While the electrical resistivity<br />

decreased linearly with increasing temperature, carrier concentration was decreased up to 400<br />

K, followed by a rapid increase at higher temperatures. The Hall mobility has peak value<br />

around 380 K and decreased due to increasing charge carrier, which is thermally activated<br />

excess carrier, as temperature increase. In situ high-temperature electrical resistivity and Hall<br />

measurements have proven useful tools for establishing doping effect in perovskite<br />

La0.01Ba0.99TiO3 and to screen it for potential technological applications. The capacitancetemperature<br />

measurement with different frequency shows that the phase transition around 420<br />

K is occurred.<br />

Mobility � (cm 2 /V.s )<br />

0.8<br />

0.6<br />

0.4<br />

0.2<br />

0.0<br />

250 300 350 400 450 500 550<br />

Temperature (K)<br />

(a)<br />

Dielectric constant (�')<br />

Fig. Hall mobility (a), dielectric constant (b) as function <strong>of</strong> temp. for the reduced La0.01Ba0.99TiO3<br />

P- 36<br />

80<br />

75<br />

70<br />

65<br />

60<br />

1kHz<br />

10kHz<br />

100kHz<br />

300 400 500 600<br />

Temperature (K)<br />

(b)


<strong>Poster</strong> session I<br />

High piezoelectric coefficient <strong>of</strong> lead-free KNN-based thin films<br />

for MEMS application<br />

Hae Jin Seog 1 , Sun-Young Lee 1 , Chang Won Ahn 1 , jin Ho Choi 1 , Seung Ho Han 2<br />

and Ill Won Kim 1*<br />

1 Department <strong>of</strong> Physics and Energy Harvest-Storage Research Center,<br />

<strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

2 Convergence Components R&D Division, KETI, Seongnam 463-816, South Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimiw@mail.ulsan.ac.kr<br />

Lead-free piezoelectric materials have been receiving special attention due to the recent<br />

environmental issues. K0.5Na0.5NbO3 (KNN) is a promising lead-free candidate material, as it<br />

has a good ferroelectric and piezoelectric properties as well as biocompatibility. Recently,<br />

Saito et al. reported that most <strong>of</strong> the piezoelectric properties are comparable to those <strong>of</strong> PZT.<br />

However, densification <strong>of</strong> KNN ceramics is reported to be difficult. Thin film fabrication <strong>of</strong><br />

KNN-based thin film is even more challenging due to added complexity in the process<br />

compared to bulk ceramic fabrication.<br />

We have fabricated Li, Ta and Mn doped KNN thin films on Pt substrates by using the<br />

chemical solution deposition method. Studies about the partial substitution <strong>of</strong> the Li for A-site<br />

and Ta for B-site atoms in the KNN films were carried out to improve the ferroelectric and<br />

piezoelectric.[1,2] Ta doped KNN films exhibited a well-saturated piezoelectric hysteresis<br />

loop with a effective piezoelectric coefficient (d33,f) value <strong>of</strong> 61 pm/V. Mn doping effectively<br />

decrease a leakage current density due to reduction <strong>of</strong> hole conduction. Mn doped KNN film<br />

exhibits d33,f value <strong>of</strong> 80 pm/V. We are trying to fabricate KNMN cantilever. Therefore, the<br />

KNN-based thin films can be considered as an alternative for PZT films due to its comparable<br />

piezoelectric coefficient.<br />

[1] C. W. Ahn, E. D. Jeong, S. Y. Lee, H. J. Lee, I. W. Kim, Appl. Phys. Lett. 93, 212905<br />

(2008).<br />

[2] S. Y. Lee, C. W. Ahn, J. S. Kim, H. J. Lee, J. S. Choi, B. H. Park, I. W. Kim, J. Alloys and<br />

Comp. 509, L194 (2011).<br />

P- 37


<strong>Poster</strong> session I<br />

Fabrication and Characterization <strong>of</strong> Inorganic Organic Composites Using<br />

Ferroelectric Nanoplates<br />

Ryo Kishimoto 1 , Masafumi Kobune 1* , Hiroshi Nishioka 1 , Takeyuki Kikuchi 1 ,<br />

Hajime Kishi 1 , Hironori Fujisawa 1 , Seiji Nakashima 1 , Masaru Shimizu 1<br />

and Satoshi Kimura 2<br />

1 Graduate School <strong>of</strong> Engineering, <strong>University</strong> <strong>of</strong> Hyogo, 2167 Shosha, Himeji, Hyogo 671-<br />

2201, Japan<br />

2 Seiko Epson Corporation, Fujimi Plant 281 Fujimi, Fujimi-machi, Suwa-gun, Nagano 399-<br />

0293, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : kobune@eng.u-hyogo.ac.jp<br />

In the present report, the fabrication <strong>of</strong> ferroelectric Bi3.25Nd0.75Ti3O12 (BNT-0.75)<br />

nanoplate-epoxy resin composites was attempted by introducing epoxy resin to the space<br />

between BNT nanoplates on 3.0-�m-thick BNT(100)/(010) film/Nb:TiO2(101) substrate with<br />

0.79 mass% Nb. a- and b-axis-oriented BNT nanoplates, 3.0 �m thick, were fabricated on<br />

conductive Nb:TiO2(101) substrates with 0.79 mass% Nb at 650 o C by high-temperature<br />

sputtering. The fabricated nanoplates had a good polarization-electric field (P-E) hysteresis<br />

loop shape with a remanent polarization (2Pr) <strong>of</strong> 29 �C/cm 0 and coercive field (2Ec) <strong>of</strong> 297<br />

kV/cm. After organic film fabricated on the BNT nanoplates by spin-coating process using<br />

the epoxy resin solution added with an epoxy-curing agent and a catalytic agent, the hardened<br />

film was prepared by curing it in two stages (120 o C, 1 h and 170 o C, 2 h) under vacuum. After<br />

surface grinding to eliminate an extra resin, effective piezoelectric coefficients (d33) and<br />

polarization reversal characteristics <strong>of</strong> the resulting composites were measured using a<br />

piezoresponse force microscope (PFM) system. Figure 1 shows surface atomic force<br />

microscope (AFM) images <strong>of</strong> the inorganic-organic composite before and after the<br />

polarization reversal treatment. Figure 1(b) shows that the upper half part in the square was<br />

applied by downward bias <strong>of</strong> DC 40V to the sample, whereas the lower half part was applied<br />

by upward bias <strong>of</strong> the same voltage.<br />

Consequently, the polarizationreversed<br />

BNT nanoplates appeared<br />

as some longitudinal black bars in<br />

the lower half part in the square <strong>of</strong><br />

Fig. 1(b).<br />

Fig. 1. Surface AFM images <strong>of</strong> BNT nanoplate-epoxy<br />

resin composite (a) before and (b) after polarization<br />

reversal treatment.<br />

P- 38


<strong>Poster</strong> session I<br />

Evaluation <strong>of</strong> switching charge density <strong>of</strong> PbTiO3 nanoislands by atomic<br />

force microscopy<br />

Masashi Igawa* , Seiji Nakashima, Hironori Fujisawa, and Masaru Shimizu<br />

Graduate School <strong>of</strong> Engineering, <strong>University</strong> <strong>of</strong> Hyogo, 2167 Shosha, Himeji,<br />

Hyogo 671-2201, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : er12t002@steng.u-hyogo.ac.jp<br />

We have already reported fabrication and ferroelectric properties <strong>of</strong> self-assembled<br />

PbTiO3 nanoislands epitaxially grown on Pt electrodes by MOCVD. Piezoresponse force<br />

microscopy (PFM) revealed that piezoelectric coefficient d33 was decreased with their height<br />

less than 10nm. In this study, we evaluated the switching charge density (Qsw) <strong>of</strong> individual<br />

epitaxial PbTiO3 nanoisland by atomic force microscopy (AFM).<br />

PbTiO3 nanoislands with an average height <strong>of</strong> 4nm<br />

and width <strong>of</strong> 55nm were epitaxially grown on Pt/Ir/SrTiO3<br />

substrates by MOCVD, as shown in Fig.1. In our<br />

measurements, a conductive AFM tip was directly<br />

contacted to individual PbTiO3 nanoisland as a top<br />

electrode. A difficulty <strong>of</strong> AFM measurements <strong>of</strong> the<br />

switching charge is in that the switching charge is much<br />

smaller than charging and discharging charges to the<br />

parasitic capacitance. In our AFM system, the parasitic Fig.1 AFM image <strong>of</strong> PbTiO3<br />

capacitance was reduced to be less than 100 fF. Switching nanoislands.<br />

charge was measured by applying a pulse train with a<br />

preceding negative pulse, two consecutive positive pulses<br />

and two negative pulses, as shown in Fig.2. The amplitude<br />

and width were 2V and 400ns, respectively. The charge<br />

Q1 includes charges transferred by both polarization<br />

switching and leakage, and Q2 corresponds to leakage<br />

because polarization was switched by the first pulse and<br />

not by the second one. Therefore, the difference between<br />

Q1 and Q2, Q1-Q2, corresponds to the switching charge,<br />

which was calculated to be 4.9 fC for the nanoisland. The<br />

charge <strong>of</strong> 4.9 fC corresponds to a switching charge density Fig.2 An applied voltage pulse<br />

train and switching charge<br />

<strong>of</strong> 135�C/cm2. At the conference, a size dependence <strong>of</strong><br />

transient <strong>of</strong> a PbTiO3 nanoisland<br />

Qsw will also be discussed.<br />

with a height <strong>of</strong> 3.3nm and a<br />

width <strong>of</strong> 61×60nm.<br />

P- 39


<strong>Poster</strong> session I<br />

Magnetoelectric Properties <strong>of</strong> CuFe2O4/BaTiO3 Bi-layer Thin Films<br />

Dong Jin Yoon 1 , Jungho Ryu 2 , Sung-Ok Hwang 3 , Jai-Yeoul Lee 1<br />

and Hee Young Lee 1 *<br />

1,3 Department <strong>of</strong> Materials Science and Engineering, Yeungnam <strong>University</strong>,<br />

Gyeongsan, 712-749, Korea<br />

2 Functional Ceramics Research Group, Korea Institute <strong>of</strong> Materials Science (KIMS),<br />

Changwon, 641-831, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: hyulee@yu.ac.kr<br />

Multiferroic properties <strong>of</strong> CuFe2O4/BaTiO3 thin films grown on highly textured<br />

Pt(111)/TiO2/SiO2/Si(100) substrates were studied. Sintered BaTiO3 and CuFe2O4 pellets<br />

prepared by the conventional mixed oxide process were used as targets during deposition by<br />

the ion-beam sputtering and the pulsed laser deposition technique. The film structure is <strong>of</strong> bilayer<br />

type, where BaTiO3 layer lies underneath <strong>of</strong> CuFe2O4 layer. CuFe2O4/BaTiO3 thin films<br />

were annealed at temperature between 650℃ and 750℃, followed by either fast-cooling or<br />

slow-cooling treatment. Ferroelectric and electrical properties were measured using<br />

ferroelectric test system, digital multimeter, and impedance analyzer. Magnetic hysteresis (M-<br />

H) behavior at room temperature was measured using vibration sample magnetometer (VSM)<br />

with saturation magnetization (Ms) and coercivity (Hc) values <strong>of</strong> 280 emu/cm 3 and 225 Oe,<br />

respectively. We have previously reported the multiferroic behavior <strong>of</strong> the similar structure,<br />

i.e. Fe-BaTiO3 bi-layer thin films, in which the possibility <strong>of</strong> ferroelectric-ferromagnetic<br />

coupling was suggested as a result <strong>of</strong> interfacial reaction between the layers. Top Fe layer,<br />

however, is not chemically stable in an oxidizing atmosphere, and as a result CuFe2O4 spinel<br />

film replaced Fe layer in this study.<br />

Keywords : multiferroic, magnetoelectric, ferroelectricity, magnetic properties<br />

P- 40


<strong>Poster</strong> session I<br />

Electrical properties <strong>of</strong> (Bi0.9A0.1)(Fe0.975Cr0.025)O3 (A=Ho, Tb and Sm) thin<br />

films prepared by chemical solution deposition<br />

H. J. Kim, S. S. Kim 1 *, C. M. Raghavan, J. W. Kim, Y. J. Kim, J. -J. Oak, W. -J. Kim 1 ,<br />

M. H. Kim 2 and T. K. Song 2 ,<br />

1 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon, Gyeongnam 641-773,<br />

Korea<br />

2 School <strong>of</strong> Nano & Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Changwon, Gyeongnam 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : sskim@changwon.ac.kr<br />

The small polarization as well as the high leakage current is the main issue for the<br />

application <strong>of</strong> the BiFeO3 (BFO). In order to improve the polarization properties <strong>of</strong> the BFO<br />

thin film, there were some research focused on Bi-site substitution with rare earth atom and<br />

Fe-site substitution with Cr atom. Pure BFO and co-substituted (Bi0.9A0.1)(Fe0.975Cr0.025)O3 (A<br />

= Ho, Tb and Sm) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a<br />

chemical solution deposition method. The micro-structures <strong>of</strong> the thin films were<br />

characterized by means <strong>of</strong> X-ray diffraction, Raman scattering spectra and scanning electron<br />

microscope. The ferroelectric properties and the leakage current density <strong>of</strong> the pure BFO and<br />

the co-substituted (Bi0.9A0.1)(Fe0.975Cr0.025)O3 (A = Ho, Tb and Sm) thin films were measured<br />

using a ferroelectric tester and an electrometer.<br />

P- 41


<strong>Poster</strong> session I<br />

Analysis for crystal structure <strong>of</strong> rare-earth substituted BiFe0.975Zn0.025O3-δ<br />

thin films and their electrical properties<br />

J. W. Kim, S. S. Kim 1 *, H. J. Kim, C. M. Raghavan, Y. J. Kim, J. -J. Oak, W. -J. Kim 1 ,<br />

M. H. Kim 2 and T. K. Song 2<br />

1 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon, Gyeongnam 641-773,<br />

Korea<br />

2 School <strong>of</strong> Nano & Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Changwon, Gyeongnam 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : sskim@changwon.ac.kr<br />

BiFeO3 (BFO) is the only single-phase multiferroic material so far be discovered, which<br />

has transition temperatures (Curie temperature, Néel temperature) above room temperature.<br />

Therefore, BFO has been widely studied in recent years because <strong>of</strong> potential applications at<br />

room temperature. However, one <strong>of</strong> the major problems <strong>of</strong> BFO is high leakage current. The<br />

low leakage current density in BFO thin films can be obtained by optimizing growth<br />

condition, such as annealing atmosphere in chemical solution deposition. And the siteengineering<br />

concept is also useful to reduce the leakage current in BFO thin films. Pure BFO<br />

and co-doped (Bi0.9RE0.1)(Fe0.975Zn0.025)O3-δ (RE = Dy, Eu and La) thin films were prepared<br />

on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. X-ray<br />

diffraction analysis and Raman scattering spectrum reveal that all samples have a single-phase<br />

rhombohedral perovskite structure. Surface morphology and film thickness were analyzed by<br />

scanning electron microscope. The electrical properties <strong>of</strong> the thin films were investigated by<br />

P-E hysteresis loops and leakage current conduction behavior measurements.<br />

P- 42


<strong>Poster</strong> session I<br />

Epitaxial growth <strong>of</strong> PbVO3 thin films with a large tetragonality factor<br />

and their polarization reversal at nano-scale<br />

R. H. Shin 1 , W. Jo 1,* , Y.-S. Seo 2 and J. S. Ahn 2<br />

1<br />

Department <strong>of</strong> Physics, Ewha Womans <strong>University</strong>, Seoul 120-750, Korea<br />

2 Department <strong>of</strong> Physics, Pusan National <strong>University</strong>, Busan 609-735, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: wmjo@ewha.ac.kr<br />

Polar magnetic PbVO3 (PVO) is one <strong>of</strong> the promising multiferroics because it has C-type<br />

antiferromagetic ordering owing to dxy orbital and can be ferroelectric due to ABO3 structure<br />

with a large tetragonality. Recently, a gigantic electrical polarization <strong>of</strong> 152 μC/cm 2 was<br />

predicted in PVO by the Berry-phase calculation [1]. However, no one has observed yet the<br />

polarization <strong>of</strong> PVO experimentally even down to 77 K. With a corner-shared pyramidal<br />

structure <strong>of</strong> VO4, the short bond-length is one <strong>of</strong> the reasons to suppress their polarization [2].<br />

The bonding length might be extended by controlling tetragonality in epitaxial thin films.<br />

We elaborated to growth epitaxial PVO thin films by a pulsed laser deposition method using a<br />

sintered PbVOx ceramic target. LaAlO3 (001) substrates were used because a-axis constant <strong>of</strong><br />

PVO is 3.79 Å, which is the same as that <strong>of</strong> LaAlO3. Control <strong>of</strong> oxygen partial pressure<br />

during the deposition turns out to be crucial for the PbVO3 single-phase. Thus, we used a<br />

mixed gas <strong>of</strong> argon and oxygen during deposition and in-situ annealing process, which is a<br />

severely reducing condition against a normal synthesis <strong>of</strong> oxide materials. Laser fluence was<br />

controlled in a range <strong>of</strong> 1.0 ~ 3.5 J/cm 2 . Crystallinity <strong>of</strong> the PVO thin films was investigated<br />

by x-ray diffraction patterns. The films were epitaxially grown along c-axis normal to the<br />

substrate with larger c lattice constant than bulk, which may due to compressive stress<br />

between the film and the substrate. Local electrical polarization was studied using<br />

electrostatic force microscopy in PVO thin films with different buffer layers. We will discuss<br />

how to improve the structure <strong>of</strong> the PVO thin films and their electrical properties to show a<br />

gigantic polarization that was predicted.<br />

[Reference]<br />

1. Y. Uratani, T. Shishidou, F. Ishii, and T. Oguchi, Jpn. J. Appl. Phys. 44, 7130 (2005).<br />

2. A. Kumar, L. W. Martin, S. Denev, J. B. Kortright, Y. Suzuki, R. Ramesh, and V. Gopalan,<br />

Phys. Rev. B, 75, 060101(R) (2007).<br />

P- 43


<strong>Poster</strong> session I<br />

The effects <strong>of</strong> Mn contents on electrical properties <strong>of</strong> BiFeO3<br />

Dalhyun Do 1* , Myang Hwan Lee 1 , Tae Kwon Song 1 , Myong-Ho Kim 1 ,<br />

Won Jeong Kim 2 , Yeon Soo Sung 3 and Sunggi Baik 3<br />

1 School <strong>of</strong> Nano and Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Changwon 641-773, Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon 641-773, Korea<br />

3 Department <strong>of</strong> Materials Science and Engineering, Pohang <strong>University</strong> <strong>of</strong> Science and<br />

Technology, Pohang 790-784, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: ddo@changwon.ac.kr<br />

Multiferoic BiFeO3 (BFO) thin films exhibit coupled electric, magnetic, and structural<br />

order parameters that result in simultaneous ferroic properties at room temperature. One <strong>of</strong> the<br />

limitations for the use <strong>of</strong> BFO thin films in electronic devices such as new function memory<br />

devices and spintronics is high leakage current that is mainly originated from the presence <strong>of</strong><br />

oxygen vacancies, Fe 2+ ions, impurity phases, etc. Thus it is necessary to control the leakage<br />

current so that BFO thin films can be utilized for new function memory devices. In this study,<br />

we deposited Mn-doped BFO thin films using a pulsed laser deposition method. The effects<br />

<strong>of</strong> Mn contents on ferroelectric properties and leakage current were investigated.<br />

P- 44


<strong>Poster</strong> session I<br />

Spin waves measurement <strong>of</strong> room-temperature multiferroic BiFeO3<br />

Jaehong Jeong 1 , E. A. Goremychkin 2 , T. Guidi 2 , K. Nakajima 3 , Gun Sang Jeon 4 ,<br />

Shin-Ae Kim 5 , S. Furukawa 6 , Yong Baek Kim 6 , Seongsu Lee 5 , V. Kiryukhin 7 ,<br />

S-W. Cheong 7 , and Je-Geun Park 1,8*<br />

1 FPRD Department <strong>of</strong> Physics & Astronomy, Center for Strongly Correlated Materials Research,<br />

Seoul National <strong>University</strong>, Seoul 151-747, Korea<br />

2 ISIS Facility, STFC Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, UK<br />

3 Neutron Science Section, MLF Division, J-PARC Center, Tokai, Ibaraki 319-1106, Japan<br />

4 Department <strong>of</strong> Physics, Ewha Womans <strong>University</strong>, Seoul 120-750, Korea<br />

5 Neutron Science Division, Korea Atomic Energy Research Institute, Daejeon 305-353, Korea<br />

6 Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> Toronto, Toronto M5S 1A7, Canada<br />

7 Rutgers Center for Emergent Materials and Department <strong>of</strong> Physics and Astronomy, Rutgers<br />

<strong>University</strong>, Piscataway NJ 08854, USA<br />

8 Center for Korean J-PARC Users, Seoul National <strong>University</strong>, Seoul 151-747, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : jgpark10@snu.ac.kr<br />

Multiferroic materials are one <strong>of</strong> most challenging topics in the condensed matter<br />

physics not only for its fundamental importance but also for huge future applications.<br />

Although there are several systems that have multiferroic behavior, few compounds have both<br />

magnetic and ferroelectric transition temperatures above room temperature. BiFeO3 is<br />

probably the only exception with anti-ferromagnetic transition at TN=650 K and ferroelectric<br />

transition at TC=1100 K.<br />

In order to understand the microscopic magnetic interactions in BiFeO3, we have<br />

carried out inelastic neutron scattering experiments on ten co-aligned single crystals using<br />

AMATERAS beamline at J-PARC and MERLIN beamline at ISIS. In particular, we used a<br />

so-called sample rotation method on MERLIN and could map out the full three-dimensional<br />

magnon dispersion [1]. We also succeeded in measuring the full phonon dispersion curves.<br />

For the analysis, we have calculated the magnon dispersion and conducted Monte-Carlo<br />

simulation using Heisenberg Hamiltonian with two exchange parameters between the nearest<br />

and the next nearest neighbors. A Dzyaloshinskii-Moriya-like term that possibly arises from<br />

the spiral magnetic structure <strong>of</strong> BiFeO3 was also examined for both calculations. We could<br />

determine, by carefully examining the AMATERAS and MERLIN data, the exchange<br />

parameters that are consistent with both experimental results and the Monte-Carlo simulations.<br />

We will also present our measured phonon dispersion curves.<br />

1) Jaehong Jeong et al., Phys. Rev. Lett. 108, 077202 (2012)<br />

P- 45


<strong>Poster</strong> session I<br />

Real-space imaging <strong>of</strong> ferroelectric and structural antiphase domain walls<br />

in Hexagonal YMnO3<br />

K. Kobayashi 1 , K. Kurushima 2 , Y. Togawa 1 , Y. Horibe 3 , S-W. Cheong 3<br />

and S. Mori 1,*<br />

1 Osaka Prefecture <strong>University</strong>, Sakai, Osaka 599-8531 Japan<br />

2 Toray Research Center, Ohtsu, Shiga 520-8567, Japan<br />

3 Department <strong>of</strong> Physics and Astronomy, Rutgers <strong>University</strong>, Piscataway, NJ, 08854, USA<br />

* E-mail address <strong>of</strong> the corresponding author : mori@mtr.osakafu-u.ac.jp<br />

Hexagonal manganites RMnO3 with R=Ho-Lu, Y and Sc exhibit have received much<br />

attention because <strong>of</strong> their intriguing physical properties such as magnetoelectric effect [1]. In<br />

the case <strong>of</strong> YMnO3, a structural phase transition from a paraelectric P63/mmc structure to a<br />

non-centrosymmetric P63cm one takes place at about Tc~933K and a spontaneous<br />

polarization (Ps) appears along the [001] direction in the ferroelectric (FE) phase [2]. Its FE<br />

polarization was induced by a buckling <strong>of</strong> layered MnO5 polyhedra and displacements <strong>of</strong> Y<br />

ions [3]. In addition, characteristic domain structures consisting <strong>of</strong> six FE and structural<br />

antiphase domains appears in the FE phase, which can be identified as the “cloverleaf” pattern<br />

[3-5]. Here, we have investigated characteristic FE and structural antiphase domain structures<br />

in hexagonal RMnO3 (R=Y, Ho, Lu, and Yb) by the transmission electron microscopy (TEM).<br />

In the FE phase <strong>of</strong> RMnO3 characteristic domain structures with the “cloverleaf” pattern is<br />

found in the (110) plane, in addition to the (001) plane, and are inherent to the ferroelectric<br />

phase <strong>of</strong> hexagonal RMnO3 [5]. In domain configuration with the cloverleaf pattern in the<br />

(110) plane, the structural antiphase boundaries are inclined to be parallel to the [001]<br />

direction [5]. In this study, we have applied high-angle annular-dark-field (HAADF) imaging<br />

technique to hexagonal manganites [6] and mapped the atomic shifts <strong>of</strong> Y and Mn ions in the<br />

FE phase <strong>of</strong> YMnO3, in order to elucidate the structural characteristics <strong>of</strong> the domain wall<br />

structures. Two types <strong>of</strong> 180° domain walls can be identified. One is the transverse and<br />

longitudinal domain walls with atomic displacements <strong>of</strong> a/3 and the other is the transverse<br />

domain walls with atomic displacements <strong>of</strong> 2a/3. Note that a represents a unit lattice vector<br />

along the direction. In contrast, the displacements related to the MnO5 polyhedral<br />

remain intact across the domain walls. These features <strong>of</strong> the FE and structural antiphase<br />

domain walls should be important to understand unusual physical properties in hexagonal<br />

manganites.<br />

[1] T. Katsufuji et al., Phys. Rev. B 66, 104419 (2001).<br />

[2] T. Lonkai et al., Phys. Rev. B 69, 134108 (2001).<br />

[3] T. Choi et al., Nat. Matter 9, 253 (2010).<br />

[4] M. Lillenblum et al., J. Appl. Phys., 110, 052007 (2011).<br />

[5] K. Kobayashi et al., (in press).<br />

[6] Q. H. Zhang et al., Phys. Rev. B 85, 020102(R), (2012).<br />

P- 46


<strong>Poster</strong> session I<br />

Pressure-induced magnetic and ferroelectric phase transitions in<br />

Multiferroic EuMn2O5<br />

H. Kimura 1* , S. Fujiyama 1 , J. Lin 1 , M. Fukunaga 2 , Y. Noda 1 , H. Hiraka 3 , S.-A. Kim 4<br />

and C.-H. Lee 1,4<br />

1 Institute <strong>of</strong> Multidisciplinary Research for Advanced Materials, Tohoku <strong>University</strong>,<br />

Sendai 980-8577, Japan<br />

2 Department <strong>of</strong> Physics, Okayama <strong>University</strong>, Okayama 700-8530, Japan<br />

3 Institute for Material Research, Tohoku <strong>University</strong>, Sendai 980-8577, Japan<br />

4 HANARO, Korea Atomic Energy Research Institute Daejeon 305-600, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimura@tagen.tohoku.ac.jp<br />

RMn2O5 (R = Y, Bi, rare-earth) is one <strong>of</strong> the prototypical multiferroic materials that<br />

exhibit a rich variety <strong>of</strong> magnetoelectric effects. Since the successive magnetic and<br />

ferroelectric phase transitions simultaneously take place, magnetic order has been thought to<br />

be a primary order parameter for the ferroelectricity in this system. We recently have found<br />

that in EuMn2O5, in which only Mn 3+ and Mn 4+ ions are responsible for the magnetism,<br />

magnetic phase transition is induced by applying hydrostatic pressure. As temperature<br />

decreases upon p > 0.6 GPa, shown in Figure, the magnetic propagation wave vector changes<br />

from qM = (1/2, 0, 1/3) to (1/2, 0, 1/2), indicating that the period <strong>of</strong> magnetic unit cell as well<br />

as the magnetic structure change at the phase transition. Quite interestingly, the ferroelectric<br />

(FE1) – ferroelectric (FE2) phase transition concomitantly occurs at the magnetic phase<br />

transition. To clarify the relevance between the ferroelectricity and the magnetic structure, we<br />

carried out single crystal magnetic structure analysis <strong>of</strong> 153 EuMn2O5 using FONDER<br />

diffractometer in JRR-3M and 4CD in HANARO under ambient- and high-pressure. In the<br />

magnetic phase with qM = (1/2, 0, 1/3), cycloidal magnetic structure <strong>of</strong> manganese spins<br />

propagating along c-axis is realized. On the<br />

contrary in the magnetic phase with qM = (1/2, 0,<br />

1/2), the spins arrange almost collinearly along<br />

c-axis. The result indicates that the presence <strong>of</strong><br />

the cycloidal spin structure plays an important<br />

role for inducing (or reducing) the electric<br />

polarization in this compound. This work has<br />

been supported by Grants-in-aid <strong>of</strong> Scientific<br />

Research on Priority Areas (19052001), (A)<br />

(21244051), and challenging Exploratory<br />

Research (23654098).<br />

Figure: Magnetic and dielectric phase diagram<br />

as functions <strong>of</strong> temperature and hydrostatic<br />

pressure for EuMn2O5.<br />

P- 47


<strong>Poster</strong> session I<br />

Preparation <strong>of</strong> epitaxial BiFeO3 thin films by RF planar magnetron<br />

sputtering<br />

Yusuke Takada*, Shota Seto, Seiji Nakashima, Hironori Fujisawa,<br />

Masafumi Kobune and Masaru Shimizu<br />

Graduate School <strong>of</strong> Engineering, <strong>University</strong> <strong>of</strong> Hyogo, 2167 Shosha, Himeji, Hyogo, 671-<br />

2201, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : er11n018@steng.u-hyogo.ac.jp<br />

BiFeO3(BFO) is a multiferroic material which simultaneously shows ferroelectricity and<br />

antiferromagnetism. It has also been expected as one <strong>of</strong> lead-free ferroelectrics because <strong>of</strong> its<br />

large remanent polarization (Pr ~100 �C/cm 2 ) in a thin film form. BFO thin films have<br />

generally been prepared by pulsed laser deposition (PLD) and chemical solution deposition<br />

(CSD). However, it is well-known that growth <strong>of</strong> high quality BFO thin films by planar<br />

sputtering is difficult. It has been already reported that leakage current <strong>of</strong> BFO thin films can<br />

be reduced by controlling domain structure for reducing conductive 109 o domain walls. 1) In<br />

this study, we employed RF planar magnetron sputtering for BFO thin film growth and<br />

demonstrated growth <strong>of</strong> high quality BFO thin film by controlling domain structure using <strong>of</strong>fcut<br />

substrates.<br />

300-nm-thick BFO thin films were epitaxially<br />

grown on SrRuO3(SRO)(50 nm)/SrTiO3(STO)(001)<br />

with 4 ○ <strong>of</strong>f-cut along [110] direction by RF planar<br />

magnetron sputtering. Substrate temperature, sputtering<br />

pressure, Ar/O2 gas flow rate and deposition rate were<br />

fixed at 610 ○ C, 0.5 Pa, 4/2 sccm and 1.1 nm/min,<br />

respectively. Bi2O3 + �-Fe2O3 mixed and calcined<br />

powder with Bi/Fe ratio <strong>of</strong> 1.4 was used as a target<br />

because <strong>of</strong> high volatility <strong>of</strong> Bi2O3.<br />

The BFO thin film with Bi/Fe ratio <strong>of</strong> 1.0 shows a<br />

smooth surface with step and terrace structure as shown<br />

in Fig.1. PFM revealed that it has single domain<br />

structure. Figure 2 shows ferroelectric D-E hysteresis<br />

loops at RT. and frequency <strong>of</strong> 20 kHz. Remanent<br />

polarization (2Pr) and coercive filed (2Ec) were 120<br />

�C/cm 2 and 252 kV/cm, respectively. The 2Pr value<br />

shows good agreement with that <strong>of</strong> bulk single crystal. 2)<br />

By controlling Bi/Fe ratio and domain structure, the<br />

high quality BFO thin film was obtained by RF planer<br />

magnetron sputtering.<br />

1) H. W. Jang et al., Adv. Mater., 21, 817 (2009).<br />

2) D. Lebeugle et al., Appl. Phys. Lett., 91, 022907<br />

(2007).<br />

P- 48<br />

Fig.1. An AFM image <strong>of</strong> the BFO<br />

thin film.<br />

Fig.2. D-E hysteresis loops <strong>of</strong> the<br />

BFO thin film.


<strong>Poster</strong> <strong>Session</strong> II<br />

10:30 ~ 12:00, August 9<br />

Gallery, 2F, International Building


<strong>Poster</strong> session II<br />

Fabrication <strong>of</strong> PZT/ZnO core-shell nanorods with different PZT<br />

thicknesses by MOCVD<br />

Chiaki Kobayashi*, Hironori Fujisawa, Seiji Nakashima and Masaru Shimizu<br />

Graduate School <strong>of</strong> Engineering, <strong>University</strong> <strong>of</strong> Hyogo, 2167 Shosha, Himeji, Hyogo,<br />

671-2201, JAPAN<br />

* E-mail address <strong>of</strong> the corresponding author : er12n024@steng.u-hyogo.ac.jp<br />

We have demonstrated preparation and characterization <strong>of</strong> PZT/ZnO core-shell nanorods<br />

using ZnO nanorods as a positive template by metalorganic chemical vapor deposition<br />

(MOCVD). In MOCVD, since ZnO nanorods are grown by self-assembly, it is difficult to<br />

control the size, the density (the number <strong>of</strong> nanorods per unit area), and the arrangement <strong>of</strong><br />

nanorods. In this study, ZnO nanorods were prepared by 2-step growth method, and PZT/ZnO<br />

core-shell nanorods with different PZT thicknesses were fabricated.<br />

ZnO nanorods were grown in the vapor-solid (V-S) growth mode on a-sapphire substrate<br />

by MOCVD using Zn(C2H5)2 and O2 as source materials. In the V-S growth mode, the density<br />

<strong>of</strong> ZnO nanorods is determined by the diameter<br />

because they were close-packed on the substrate.<br />

Therefore, it was difficult to change the density<br />

independently <strong>of</strong> the diameter although the diameter<br />

can be controlled by the growth temperature.<br />

In the 2-step growth method, ZnO nanorods with<br />

a large diameter were deposited on a-sapphire, and<br />

subsequently ZnO nanorods with a smaller diameter<br />

were deposited on the preceeding nanorods, as shown Fig.1 FE-SEM photograph <strong>of</strong> ZnO<br />

in Fig.1. Therefore, the density <strong>of</strong> ZnO nanorods, 2.3 nanorods grown by 2-step growth<br />

method<br />

�m<br />

Fig.2 FE-SEM photograph <strong>of</strong><br />

PZT/ZnO core-shell nanorods with<br />

PZT thickness <strong>of</strong> 180 nm.<br />

-2 , was determined only by the diameter <strong>of</strong> the<br />

firstly grown nanorods, and reduced much less than<br />

that calculated from the diameter <strong>of</strong> subsequently<br />

grown ZnO nanorods, 240.6 �m -2 . By using the ZnO<br />

nanorods with a density as low as 2.3 �m -2 , PZT/ZnO<br />

core-shell nanorods with PZT thicknesses from 20 to<br />

180 nm were successfully fabricated, as shown in<br />

Fig.2. At the conference, piezo- and ferro-electric<br />

properties <strong>of</strong> the PZT/ZnO core-shell nanorods with<br />

different diameters will be also discussed.<br />

P- 49


<strong>Poster</strong> session II<br />

Local charge conductions in multiferroic BiFeO3 nanostructures<br />

Taekjib Choi 1* , Sahwan Hong 2 , Jihoon Jeon 2 , Yunseok Kim 3 , Hosang Lee 1 ,<br />

Ho-Young Joo 1 , Jinsik Choi 2 , Jin-Soo Kim 2 , Sergei V. Kalinin 3 and Baeho Park 1<br />

1 Hybrid Materials Research Center and Institute <strong>of</strong> Nanotechnology and Advanced Materials<br />

Engineering, Sejong <strong>University</strong>, Seoul 143-747, Korea<br />

2 Division <strong>of</strong> Quantum Phases & Devices, Department <strong>of</strong> Physics, Konkuk <strong>University</strong>, Seoul<br />

143-701, Korea<br />

3 The Center for Nanophase Materials Science, Oak Ridge National Laboratory, Oak Ridge,<br />

TN 37831, USA<br />

* E-mail address <strong>of</strong> the corresponding author : tjchoi@sejong.ac.kr<br />

Semiconductor multiferroic thin films and nanostructures have emerged as functional<br />

elements in oxide electronics. They consist <strong>of</strong> domain structures with switchable electric<br />

spontaneous polarization by applying external bias. Recently, remarkable charge conductions<br />

at ferroelectric domain/walls have been revealed in various ferroelectrics, demonstrating<br />

intriguing interplay between electronic transport properties and ferroelectric polarization. In<br />

this work, we report local charge conductions in BiFeO3 nanostructure coupling with local<br />

electric polarization will be presented. We have fabricated highly ordered BiFeO3 nanoislands<br />

using anodic aluminium oxide templates by pulsed-laser-deposition. Their local<br />

charge conductivity and domain structures were studied using piezoresponse force<br />

microscopy and conductive atomic force microscopy. BiFeO3 nano-islands showed a strong<br />

flexoelectric effect for charge conductions and electric polarization with a different electrode<br />

or substrate. Our results should provide a fundamental understanding <strong>of</strong> local charge<br />

conduction with domain structures in ferroelectric nanostructures.<br />

P- 50


<strong>Poster</strong> session II<br />

Intaglio Nanotemplates Based on Atomic Force Microscopy for<br />

Ferroelectric Nanodots<br />

Jong Yeog Son 1 and Young-Han Shin 2*<br />

1 Department <strong>of</strong> Applied Physics, College <strong>of</strong> Applied Science, Kyung Hee <strong>University</strong>, Suwon<br />

446-701, Korea,<br />

2 Departments <strong>of</strong> Physics, Chemistry and EHSRC, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749,<br />

Korea<br />

* E-mail address <strong>of</strong> the corresponding author : hoponpop@ulsan.ac.kr<br />

We demonstrate the nano-intaglio process to form a nanotemplate and a series <strong>of</strong><br />

nanoscale grooves using atomic force microscopy. Nanopores are hoed with a diameter <strong>of</strong><br />

20 nm on the surface <strong>of</strong> a SrTiO3 thin film epitaxially grown on an Nb-doped SrTiO3<br />

substrate using a diamond tip. For the demonstration <strong>of</strong> the nano-intaglio process, a<br />

nanotrench is intaglioed at a length <strong>of</strong> approximately 150 nm and a width <strong>of</strong> approximately 20<br />

nm. The nano-intaglio process enables the fabrication <strong>of</strong> a nanotemplate with a highest<br />

packed hexagonal array, with a density <strong>of</strong> approximately 6.0×10 11 /inch 2 . A ferroelectric<br />

poly(vinyliden fluoride-ran-trifluoroethylene: PVDF-TrFE) nanodot with a diameter <strong>of</strong> about<br />

20 nm is formed by filling a nanopore with a PVDF-TrFE solution, whose ferroelectric<br />

properties are confirmed using piezoelectric force microscopy.<br />

P- 51


<strong>Poster</strong> session II<br />

Terahertz time-domain spectroscopy study <strong>of</strong> LiNbO3<br />

Hikaru Igawa 1* , Tatsuya Mori 1 , Kei Iwamoto 2 , Naoki Toyota 2 and Seiji Kojima 1<br />

1 Graduate School <strong>of</strong> Pure and Applied Science, <strong>University</strong> <strong>of</strong> Tsukuba, Tsukuba, Ibaraki<br />

305-8573, Japan<br />

2 Department <strong>of</strong> Physics, Graduate School <strong>of</strong> Science, Tohoku <strong>University</strong>, Sendai 980-8578,<br />

Japan<br />

* E-mail address <strong>of</strong> the corresponding author : s1220414@u.tsukuba.ac.jp<br />

Temperature and frequency dependence <strong>of</strong> the dielectric properties <strong>of</strong> LiNbO3 crystals<br />

have been studied by THz time-domain spectroscopy (THz-TDS) with the use <strong>of</strong> a standard<br />

transmission configuration, covering the frequency range <strong>of</strong> 0.1 to 2.0 THz and temperature<br />

range <strong>of</strong> 5 to 300 K. LiNbO3 is an uniaxial electro-optic crystal, and Curie temperature (TC) is<br />

1463 K [1] . The measured sample was x-cut crystal, and thickness was 400 μm. The x-cut<br />

plane has the ordinary and extraordinary axis. Figure 1 shows experimental results <strong>of</strong> the<br />

complex dielectric constants at room temperature and fitting results <strong>of</strong> Lorentzian curves.<br />

Filled squares are along ordinary axis, circles are along extraordinary axis, and solid lines are<br />

fitting results. The obtained fitting parameters are following. The resonance frequency,<br />

resonance width, oscillator strength, and static dielectric constant <strong>of</strong> the ordinary axis are 4.24<br />

THz, 0.58 THz, 28.1, and 44.4 respectively. Those <strong>of</strong> the extraordinary axis are 3.82 THz,<br />

0.76 THz, 5.53, and 26.2 respectively. These results are in good agreement with the previous<br />

report [2] .<br />

�'<br />

60<br />

50<br />

40<br />

30<br />

(a)<br />

LiNbO 3<br />

Ordinary<br />

Extraordinary<br />

20<br />

0.0 0.5 1.0 1.5 2.0 2.5<br />

Frequnecy (THz) Frequency (THz)<br />

Fig. 1. (a) Real and (b) imaginary part <strong>of</strong> the dielectric constants <strong>of</strong> LiNbO3 at room<br />

References<br />

1. A. S. Barker, JR., and R. Loudon, Phys. Rev. 158, 2 (1967).<br />

2. M. Schall, H. Helm, and S. R. Keiding, Int. J. Infrared and Millimeter Waves 20, 4 (1999).<br />

�''<br />

P- 52<br />

4<br />

2<br />

0<br />

(b)<br />

0.0 0.5 1.0 1.5 2.0 2.5


<strong>Poster</strong> session II<br />

Coherent Entropy-Wave Generation in Quantum Paraelectrics<br />

Akitoshi Koreeda 1,2* , Masaki Takesada 3 and Toshirou Yagi 3<br />

1 Department <strong>of</strong> Physics, Tohoku <strong>University</strong>, Sendai 980-8578, Japan<br />

2 Japan Science and Technology Agency, PRESTO, Kawaguchi 332-0012, Japan<br />

3 Department <strong>of</strong> Physics, Hokkaido <strong>University</strong>, Sapporo 060-0810, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : kore@m.tains.tohoku.ac.jp<br />

We have recently reported that “wave <strong>of</strong> entropy or temperature”, which is also known<br />

as “second sound”, can exist in SrTiO3 and KTaO3 at cryogenic temperatures [1-3]. In this<br />

paper, we report on active generation <strong>of</strong> “coherent entropy-wave” in these systems by using<br />

laser-induced thermal grating technique. Figure 1 shows the measurement principle and the<br />

experimental results <strong>of</strong> impulsive stimulated thermal scattering (ISTS) on KTaO3. On cooling<br />

from 30K, the decay rate becomes faster according to the temperature dependence <strong>of</strong> the<br />

thermal diffusivity. However, there are a few anomalous aspects (i) the rising rate appears to<br />

become slower and the pr<strong>of</strong>ile becomes “rounder” on cooling; (ii) the decay rate does not<br />

become faster than it is predicted from the known thermal diffusivity. In Fig.1, we also show<br />

the fitted “heat-wave functions” (i.e., not an exponential function). The fitted response<br />

reproduces the observed signal quite well, implying that we are about to generate the coherent<br />

wave <strong>of</strong> heat.<br />

Figure 1. Measuring principle <strong>of</strong> ISTS (left), and temperature dependence <strong>of</strong> the observed<br />

and fitted responses (right). The fitted function is the damped oscillator function for heat.<br />

References:<br />

1. A. Koreeda, R. Takano, and S. Saikan, Phys. Rev. Lett., 99, 265502 (2007)<br />

2. A. Koreeda, R. Takano, and S. Saikan, Phys. Rev. B 80, 165104 (2009)<br />

3. A. Koreeda, R. Takano, A. Ushio, and S. Saikan, Phys. Rev. B 82, 125103 (2010)<br />

P- 53


<strong>Poster</strong> session II<br />

Brillouin scattering study <strong>of</strong> liquid-glass transitions in ternary mixture <strong>of</strong><br />

water, trehalose and ionic liquid<br />

Haruki Takayama * , Tomohiko Shibata, Takahiro Ishii and Seiji Kojima<br />

PAS, <strong>University</strong> <strong>of</strong> Tsukuba, Tsukuba, Ibaraki 305-8573, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : s1220450@u.tsukuba.ac.jp<br />

The ternary mixtures <strong>of</strong> water, sugar, ionic liquid have attracted attention as the new<br />

candidate <strong>of</strong> bioprotectants. To clarify the physical properties <strong>of</strong> supercooled liquid and<br />

glassy states at low temperatures, the liquid-glass transitions <strong>of</strong> ternary mixtures <strong>of</strong> water,<br />

trehalose and 1-butyl-3-methylimidazolium chloride were studied by Brillouin scattering. The<br />

refractive index was measured accurately as the function <strong>of</strong> content and temperature to<br />

determine elastic properties from Brillouin frequency shift and peak width. The relaxation<br />

times <strong>of</strong> structural relaxation related to a liquid-glass transition were determined as a function<br />

<strong>of</strong> temperature. It is found that Meyer-Neldel rule holds for the activation energy and<br />

prefactor <strong>of</strong> the Arrhenius law <strong>of</strong> relaxation time [1].<br />

Sound velocity (m/s)<br />

4000<br />

3500<br />

3000<br />

2500<br />

2000<br />

1500<br />

1000<br />

500<br />

0<br />

[bmim]Cl 10 wt% trehalose 50 wt%<br />

[bmim]Cl 50 wt% trehalose 10 wt%<br />

-200 -150 -100 -50 0 50 100<br />

Temperature (�C)<br />

P- 54<br />

2x10 7<br />

1x10 7<br />

0<br />

Attenuation (m -1 )<br />

Fig. 1 Temperature dependences <strong>of</strong> sound velocity and attenuation <strong>of</strong> ternary mixtures <strong>of</strong><br />

water, trehalose and 1-butyl-3-methylimidazolium chloride.<br />

Reference<br />

1. Daniele Ielmini, Mattia Boniardi, Appl. Phys. Lett. 94, (2009) 091906.


<strong>Poster</strong> session II<br />

Structural and dielectric investigation<br />

<strong>of</strong> the charge ordered organic compound α’-(BEDT-TTF)2IBr2<br />

A. Yamashita 1 , C. Hyon 1 , M. Watanabe 2 , M. Fukunaga 1,3 , K. Kobayashi 4 , R. Kumai 4 ,<br />

K. Yamamoto 5 , K. Yakushi 5 and Y. Noda 1*<br />

1 IMRAM, Tohoku <strong>University</strong>, Sendai 980-8577, Japan<br />

2 NICHe, Tohoku <strong>University</strong>, Sendai 980-8579, Japan<br />

3 Grad. Sch. <strong>of</strong> Natural Sci. and Tech., Okayama <strong>University</strong>, Tsushimanaka 700-8530, Japan<br />

4 CMRC, the High Energy Accelerator Research Organization, Tsukuba 305-0801, Japan<br />

5 IMS, National Institutes <strong>of</strong> Natural Sciences, Okazaki 444-8585, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : ynoda@tagen.tohoku.ac.jp<br />

In the conventional ferroelectric materials such like displacement type or order-disorder<br />

type ferroelectrics, electric dipole moments are essentially relating to the atomic displacement<br />

breaking the inversion symmetry. However, another possibility <strong>of</strong> ferroelectric category<br />

named “electronic-ferroelectric” has been discussed among physicists in the recent years. In<br />

electronic-ferroelectrics, ordering <strong>of</strong> electron charges in the conducting layer forms<br />

spontaneous polarization, while the atomic/molecular positions still hold inversion symmetry.<br />

Unfortunately, no electronic-ferroelectric material with reversible spontaneous<br />

polarization was found up to now. However several charge ordering materials were reported<br />

as candidate for electronic-ferroelectrics [1-4]. The semi-conductive organic charge transfer<br />

salt α’-(BEDT-TTF)2IBr2 is one <strong>of</strong> such clue. This salt exhibits three sequential phase<br />

transitions as follows; the first one is from the room temperature phase (Phase-I: SG P-1) to<br />

the higher resistive phase (Phase-II) considered as charge ordered state at 204 K, the second<br />

one is from Phase-II to Phase-III with larger SHG signal at 160 K, and the third one is from<br />

Phase-III to the nonmagnetic Phase-IV at 25 K [4]. Phase-III is considered as a clue to<br />

electronic-ferroelectric. In this study, low temperature Xray<br />

diffraction experiments were conducted to investigate<br />

the nature <strong>of</strong> each phase at BL-8A/KEK-PF. Furthermore<br />

dielectric measurements by the Double-Wave method were<br />

carried out. In Phase-II and IV, 2-fold superlattice was<br />

found, and the spatial patterns <strong>of</strong> charge ordering in Phase-<br />

II and phase-III (Fig. 1) were revealed. The other details <strong>of</strong><br />

the results will be discussed.<br />

[1] N. Ikeda et al., Nature 436(2005)1136.<br />

[2] K. Yamamoto et al., J. Phys. Soc. Jpn. 77(2008) 074709<br />

[3] M. Naka et al., J. Phys. Soc. Jpn. 79(2010) 063707<br />

[4] Y. Yue et al., J. Phys. Soc. Jpn., 78(2009) 004.<br />

P- 55<br />

Fig.1. Charge ordering<br />

pattern and conjectured<br />

dipole moment in Phase-III


<strong>Poster</strong> session II<br />

Orbital Order in YTiO3 Observed by Super Accurate Synchrotron X-ray<br />

Diffraction<br />

Terutoshi Sakakura 1* , Yoshihisa Ishikawa 1,2 , Takahiro Nakano 1 , Hiroyuki Kimura 1 ,<br />

Yukio Noda 1 , Yoshinori Tokura 3 and Shigeki Miyasaka 4<br />

1 Institute <strong>of</strong> Multidisciplinary Research for Advanced Materials, Tohoku <strong>University</strong>, 2-1-1<br />

Katahira, Aoba, Sendai 980-8577, Japan.<br />

2 High Energy Accelerator Research Organization, KEK Tokai Campus, 203-1 Shirakata,<br />

Tokai, Naka, Ibaraki 319-1106, Japan.<br />

3 Department <strong>of</strong> Applied Physics, <strong>University</strong> <strong>of</strong> Tokyo, 7-3-1 Hongo, Bunkyo,<br />

Tokyo 113-8656 Japan.<br />

4 Graduate School <strong>of</strong> Science, Osaka <strong>University</strong>, Toyonaka, 560-0043, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : sakakura@tagen.tohoku.ac.jp<br />

Orbital state is the fundamental information <strong>of</strong> a crystal structure and a chemical bond<br />

strongly relating to phase transition phenomena. Whereas orbital ordering in materials have<br />

been mainly studied via methods observing magnetic momentum distribution in real space<br />

such as polarized neutron diffraction technique, X-ray structure analysis, which observes<br />

ligand atoms simultaneously, has an advantage to investigate the mechanism. We applied<br />

super accurate X-ray diffraction using synchrotron radiation to orbital order phase <strong>of</strong> YTiO3<br />

at room temperature. Here, the meaning <strong>of</strong> super accurate is that the observed Bragg<br />

reflection intensities are almost free from multiple scattering contaminations. The experiment<br />

was carried out using four-circle diffractometer at beam line 14A at Photon Factory, Tsukuba,<br />

Japan and all integrated intensities were measured avoiding the errors caused by multiple<br />

scattering. We clearly observed quadrupoles <strong>of</strong> ordered Ti-3d orbitals (3d 1 ) as shown in Fig. 1.<br />

Four density maxima <strong>of</strong> the quadrupoles are all attracted towards the closest four Y 3+ ions and<br />

the linear combination coefficients observed are consistent with other methods and theoretical<br />

calculations. This work has been supported by Grants-in-aid <strong>of</strong> Scientific Research on (A)<br />

(21244051), and challenging Exploratory Research (23654098).<br />

P- 56<br />

Fig.1: (a) Crystal structure around<br />

TiO6 octahedron and (b) deformed<br />

electron density map (Fourier<br />

transformation <strong>of</strong> Fobs – Fcalc<br />

after refinement using neutral<br />

atoms). Four density maxima near<br />

Ti atom corresponding to Ti-3d<br />

ordered orbital locate towards the<br />

closest four Y 3+ ions.


<strong>Poster</strong> session II<br />

Large strain response in Nb-modified BNKT-ST lead-free piezoelectric<br />

ceramics<br />

Rizwan Ahmed Malik 1 , Hyoung-Su Han 1 , Hyun-Young Lee 1 , Ali Hussain 2 ,<br />

Van-Quyet Nguyen 1 , Chang-Ho Yoon 1 and Jae-Shin Lee 1,*<br />

1 School <strong>of</strong> Materials science and Engineering, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

2 School <strong>of</strong> Nano and Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Gyeongnam 641- 773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: jslee@ulsan.ac.kr<br />

Lead-free 0.96Bi1/2(Na0.84K0.16)1/2(Ti1-xNbx) O3–0.04SrTiO3 (BNKTN-ST, with x = 0.00,<br />

0.005, 0.010, 0.015, 0.020, 0.025 and 0.030) ceramics were synthesized by conventional solid<br />

state reaction method. The effect <strong>of</strong> Nb substitution on crystal structure, dielectric,<br />

ferroelectric and electric field-induced strain behavior <strong>of</strong> BNKTN-ST was investigated in<br />

detail. XRD patterns revealed the formation <strong>of</strong> pure perovskite phase with a structural<br />

transition from the coexistence <strong>of</strong> rhombohedral and tetragonal to a pseudocubic phase at x =<br />

0.020. The temperature-dependent dielectric peaks <strong>of</strong> the BNKTN-ST ceramics broadened<br />

and ferroelectric polarizations decreased with increasing Nb concentration. Ferroelectric and<br />

bipolar field induced-strain curves indicated a significant disruption <strong>of</strong> ferroelectric order<br />

upon Nb addition into BNKT-ST ceramics. This destabilization <strong>of</strong> the ferroelectric order was<br />

accompanied by an enhanced field-induced strain. A giant field-induced strain (S = 0.45%)<br />

with a normalized strain (d * 33 = Smax/Emax = 900 pm/V) was observed at 50 kV/cm at x = 0.02.<br />

These results show that Nb-modified BNKT-ST system can deliver much higher fieldinduced<br />

strain at relatively low applied electric field as compared to existing lead-free Biperovskite<br />

ceramics.<br />

P- 57


<strong>Poster</strong> session II<br />

Enhanced piezoelectric properties <strong>of</strong> lead-free (Bi0.5Na0.5)TiO3-BaTiO3 thin<br />

films by pulsed laser deposition<br />

Jin Su Park 1 , Myang Hwan Lee 1 , Da Jeong Kim 1 , Dalhyun Do 1 , Myong Ho Kim 1 ,<br />

Sang Su Kim 2 , Won Jeong Kim 2 , Sang Wook Kim 2 , Hae In Choi 2<br />

and Tae Kwon Song 1 *<br />

1 School <strong>of</strong> Nano & Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Gyeongnam 641-773, Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Gyeongnam 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : tksong@changwon.ac.kr<br />

The (Bi0.5Na0.5)TiO3-BaTiO3 based materials have been developed as a promising leadfree<br />

piezoelectric material for environmentally benign good piezoelectric devices. In this<br />

work, the 0.935(Bi0.5Na0.5)TiO3-0.065BaTiO3 (BNBT) thin films have been grown on<br />

Pt(111)/Ti/SiO2/Si substrates by a using pulsed laser deposition method. Deposition<br />

conditions were changed with oxygen pressure 100, 200, and 300 mTorr and repetition<br />

frequency at 3 Hz and 5 Hz respectively, at deposition temperature <strong>of</strong> 750 o C. Structural and<br />

electrical properties <strong>of</strong> the films were investigated by x- ray diffractometer and electrical<br />

measurement system. The BNBT thin film exhibited the remnant polarization (2Pr) <strong>of</strong> 14<br />

�C/cm 2 deposited at 3 Hz and 300 mTorr. The piezoelectric responses <strong>of</strong> the thin films were<br />

investigated using piezoelectric force microscopy with a lock in amplifier. The thin films<br />

exhibited piezoelectric properties <strong>of</strong> d33 value <strong>of</strong> 150 pm/V.<br />

P- 58


<strong>Poster</strong> session II<br />

Na excess effects on dielectric and piezoelectric properties <strong>of</strong> lead free<br />

(Na0.53+xK0.47)(Nb0.55Ta0.45)O3 ceramics.<br />

S. Y. Lim 1 , G. H. Ryu 1 , A. Hussain 1 , D. Do 1 , T. K. Song 1 , M. H. Kim 1,* and W. J. Kim 2<br />

1 School <strong>of</strong> Nano & Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Gyeongnam 641-773, Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Gyeongnam 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : mhkim@changwon.ac.kr<br />

Lead-based ceramics are widely used for piezoelectric and ferroelectric applications.<br />

However, lead oxide present in these materials not only pollutes the environment but also<br />

harms human health. Therefore lead-free ceramics are urgently required replace theses toxic<br />

lead-based materials. In this regard (Na0.5K0.5)NbO3 based ceramics are considered most<br />

promising candidate materials for lead-free piezoelectric and ferroelectric applications. In this<br />

work, we have investigated the effect <strong>of</strong> Na excess on the dielectric piezoelectric properties <strong>of</strong><br />

(Na0.53+xK0.47)(Nb0.55Ta0.45)O3 (NKNT) ceramics. A high piezoelectric coefficient d33= 330<br />

pC/N was obtained at x= 0.015. These results show that NKNT ceramics are highly promising<br />

material for lead-free piezoelectric applications.<br />

P- 59


<strong>Poster</strong> session II<br />

Effect <strong>of</strong> the Porosity on Templated Grain Growth Behavior in (K,Na)NbO3<br />

Ceramics<br />

J. H. Choi 1 , K.W. Chae 2 , J.S. Kim 1 and C.I. Cheon 1,2*<br />

1<br />

Department <strong>of</strong> Semiconductor & Display Engineering, Hoseo <strong>University</strong><br />

2<br />

Department <strong>of</strong> Materials Science and Engineering, Hoseo <strong>University</strong>, Baebang, Asan,<br />

Chungnam, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : cicheon@hoseo.edu<br />

Recently, lead-free piezoelectric ceramics have been researched for replacing<br />

Pb(Zr,Ti)O3 (PZT)-based ceramics due to environmental restrictions. (K,Na)NbO3 (KNN)based<br />

piezoelectric ceramics show the best piezoelectric properties among several lead-free<br />

piezoelectric compositions like (Bi,Na)TiO3, Bi-layered structure ferroelectrics, etc. The<br />

KNN ceramic is, however, thought to replace Pb-based piezoelectric ceramics in limited<br />

application fields due to its inferior piezoelectric properties to the Pb-based one.<br />

Textured ceramics prepared by template grain growth (TGG) have been known to show<br />

superior piezoelectric properties to the conventional polycrystalline ceramics. In KNN<br />

ceramics, the TGG has been occurred only with the sample with sintered density higher than<br />

92% because the pore-drag force suppresses the grain boundary migration in porous samples.<br />

The porosity seems to be one <strong>of</strong> the important factors for templated grain growth <strong>of</strong> KNNbased<br />

ceramics. However, it was confirmed that the formation <strong>of</strong> the liquid phase was<br />

necessary for the TGG in other piezoelectric ceramics.<br />

The purpose <strong>of</strong> this study is to understand the effect <strong>of</strong> the porosity on the TGG behavior<br />

in KNN ceramics with or without the dopant (CuO) which forms liquid phase during sintering.<br />

NaNbO3 templates, (K, Na) NbO3 powder, and CuO were mixed by ball milling. NaNbO3<br />

seed crystals were prepared by molten salt method. The slurry was tape-casted, laminated, cut,<br />

and burned out the binder. The green density <strong>of</strong> the sample was enhanced by cold-isostatic<br />

pressing (CIP) after binder burn-out. The pressure was controlled from 0 to 150MPa during<br />

CIP in order to prepare the samples with various green densities. The samples were sintered at<br />

1100 ~ 1175 ℃ for 4 hours. The sintered density, microstructure, and the degree <strong>of</strong> texturing<br />

were investigated. The dielectric and piezoelectric properties were also analyzed. The TGG<br />

behaviors for KNN ceramics with various densities were compared. The effect <strong>of</strong> the porosity<br />

on the TGG behavior and piezoelectric properties in textured KNN ceramics will be presented.<br />

P- 60


<strong>Poster</strong> session II<br />

Low-frequency Impedance Spectroscopy <strong>of</strong> BiAlO3 modified<br />

Bi0.5(Na0.75K0.25)0.5TiO3 lead-free piezoelectric ceramics<br />

Amir Ullah, Aman Ullah, Chang Won Ahn, Bong Chan Park and Ill Won Kim *<br />

Department <strong>of</strong> Physics and Energy Harvest-Storage Research Center, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>,<br />

<strong>Ulsan</strong> 680-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimiw@mail.ulsan.ac.kr<br />

We have synthesized lead-free piezoelectric ceramics (1-x)Bi0.5 (Na0.75K0.25)0.5TiO3-<br />

xBiAlO3 (BNKT-BA, 0 ≤ x ≤ 0.10) by a solid state reaction method. The effect <strong>of</strong> varying BA<br />

concentration on various properties <strong>of</strong> BNKT ceramics has been investigated. X-ray<br />

diffraction (XRD) revealed a pure perovskite phase for composition x ≤ 0.050. The real part<br />

<strong>of</strong> dielectric constant was investigated over a wide range <strong>of</strong> temperature (0 ~ 500 o C) and<br />

frequency (0.01 ~ 100 KHz). The depolarization temperature (Td) and maximum temperature<br />

(Tm) were found around 120 o C and 294 o C, respectively. Dielectric studies revealed that the<br />

compound has diffused nature and that relaxor behavior occurs at a temperature around (Td).<br />

Analyzing the complex impedance relaxation through a Cole-Cole plot, we found the<br />

frequency dependence relaxation behavior in the material. The thermal activation energy for<br />

conduction process was calculated from the slopes <strong>of</strong> ac conductivity at 1Hz and were found<br />

1.22, 0.840, 1.014, 0.899eV for x = 0, 0.050, 0.075 and 0.100, respectively. The magnitude<br />

<strong>of</strong> Z΄ (real impedance) is observed to decrease with increasing temperature and frequency.<br />

P- 61


<strong>Poster</strong> session II<br />

Ferroelectric and Piezoelectric Properties <strong>of</strong> Polycrystalline PbTiO3 Film<br />

with Nanograin<br />

Jong-Pil Lee 1 , Soo Whan Lee 2 , Jeong Keun Lee 2 , Yun-Soo Lim 1 , Jungho Ryu 3 ,<br />

Dong-Soo Park 3 and Dae-Yong Jeong 2*<br />

1 Department <strong>of</strong> Materials Sci. & Eng., Myongji <strong>University</strong>, Gyeonggi 449-728, Korea<br />

2 School <strong>of</strong> Materials Sci. & Eng., Inha <strong>University</strong>, Incheon 402-751, Korea<br />

3 Functional Ceramics Research Group, KIMS, Gyeongnam 641-831, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : dyjeong@inha.ac.kr<br />

PbTiO3 is a typical ferroelectric material <strong>of</strong> tetragonal crystal structure with large c/a<br />

ratio. Due to large c/a ratio, pure polycrystalline film or bulk has not been fabricated and<br />

consequently ferroelectric and piezoelectric properties were not reported. Instead PbTiO3 was<br />

grown epitaxially on such a SrTiO3 single crystal substrate. It is known that nano-grain<br />

ferroelectric materials show the different behavior from macro grain materials. In this<br />

presentation, we fabricated the polycrystalline PbTiO3 film with nano grain and high density.<br />

XRD revealed that crystal structure was distorted and c/a was dramatically reduced. PbTiO3<br />

film showed clear ferroelectric behavior and larger dielectric constant that reported before. In<br />

addition, PbTiO3 film showed ~ 50 o C higher phase transition temperature.<br />

P- 62


<strong>Poster</strong> session II<br />

Piezoelectric Enhancement <strong>of</strong> Relaxor-based Lead-free Piezoelectric<br />

Ceramics by Nanodomain Engineering<br />

Ichiro Fujii 1 , Ryuta Mitsui 1 , Kouichi Nakashima 1 , Nobuhiro Kumada 1<br />

and Satoshi Wada 1*<br />

1 Material Science and Technology, Interdisciplinary Graduate School <strong>of</strong> Medical and<br />

Engineering, <strong>University</strong> <strong>of</strong> Yamanashi, 4-4-37 takeda, K<strong>of</strong>u, Yamanashi 400-8510, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : swada@yamanashi.ac.jp<br />

It is well known that Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) and Pb(Mg1/3Nb2/3)O3 -PbTiO3<br />

(PMN-PT) crystals exhibit high piezoelectric performances owing to their engineered domain<br />

configuration. Recently, it was reported that piezoelectric constant d33 <strong>of</strong> the PZT single<br />

crystals was around 1,400 pC/N by Ye et. al., and lower than those <strong>of</strong> PZN-PT and PMN-PT<br />

single crystals. These results suggested that domain engineering might be the best way to<br />

enhance the piezoelectricity, and relaxor-based ferroelectrics could be suitable for the domain<br />

engineering. This is because that for normal ferroelectrics such as BaTiO3 (BT) and KNbO3<br />

(KN), to control domain configuration and domain wall density, the microstructure <strong>of</strong><br />

ceramics must be controlled such as grain size, density, orientation and etc. On the other<br />

hand, for the relaxor-based ferroelectrics, the domain configuration was dependent on<br />

chemical composition and orientation. This means that if relaxor-based lead-free<br />

ferroelectrics are prepared, it can be expected that they might have high piezoelectric<br />

performances. Recently, we reported that BT-Bi(Mg1/2Ti1/2)O3 (BT-BMT) was relaxor<br />

ferroelectrics with high Tmax over 250 ˚C. Thus, it is possible to control domain<br />

configurations by solid solution system between the above relaxors and normal ferroelectric<br />

such as BiFeO3 (BF) with high Tc <strong>of</strong> 830 ˚C. In this study, the BT-BMT-BF system<br />

ceramics were prepared using a conventional solid–state reaction and their crystal structure<br />

and electrical properties were investigated. A single phase <strong>of</strong> perovskite was prepared for<br />

these ceramics with various compositions. TEM observation revealed that BT-BMT had no<br />

domain configuration while BF-rich ceramics had normal rhombohedral domain<br />

configurations. Moreover, the ceramic with the intermediate composition between relaxor<br />

and BF had nanodomain configuration with domain sizes less than 50 nm. For the ceramics,<br />

the temperature dependences <strong>of</strong> dielectric constants were measured at various frequencies,<br />

and the Tmax was determined. As the results, the Tmax increased with increasing BF content,<br />

while Tmax decreased with increasing BT content. Finally, their strain vs. electric-field<br />

behaviors were measured, and the relaxors showed typical electrostrictive behavior while BFrich<br />

ceramics showed typical butterfly-like ferroelectric strain behavior. For the ceramics<br />

with nanodomain configuration, the strain curve with hysteresis-less and high slope was<br />

clearly observed and the apparent d33* (Smax/Emax) from the slope was over 850 pC/N.<br />

P- 63


<strong>Poster</strong> session II<br />

Piezoelectric Properties <strong>of</strong> Ternary Pb(Mn1/3Nb2/3)O3-PbTiO3-PbZrO3<br />

System Solid Solutions<br />

Haruka Okuda * , Masafumi Kobune and Hiroshi Nishioka<br />

Graduate School <strong>of</strong> Engineering, <strong>University</strong> <strong>of</strong> Hyogo, 2167 Shosha, Himeji,<br />

Hyogo 671-2201, Japan<br />

* E-mail address <strong>of</strong> the corresponding author: et12b016@steng.u-hyogo.ac.jp<br />

Recently, high power piezoelectric materials are required to apply for ultrasonic<br />

vibrators and piezoelectric transformers. For these applications, a piezoelectric materials<br />

which have low mechanical fatigue under large amplitude drive and high conversion<br />

efficiency from mechanical energy to electrical energy is needed. The ceramics for high<br />

power piezoelectric materials should have a high piezoelectric constant d, a high mechanical<br />

quality factor Qm, and a large electromechanical coupling factor k. In the present study, to<br />

develop the piezoelectric material with excellent piezoelectric parameters described above,<br />

piezoelectric properties <strong>of</strong> ternary Pb(Mn1/3Nb2/3)O3-PbTiO3-PbZrO3 (PMnN-PT-PZ) system<br />

solid solutions were investigated in details.<br />

Reagent-grade PbO, TiO2, ZrO2, MnCO3・0.46H2O and Nb2O5 were used as starting<br />

materials. PMnN-PT-PZ powder was fabricated by a two-step solid-state reaction using a<br />

columbite precursor. The powder was pressed into discs and sintered at 1220 o C for 3 h in air.<br />

The crystalline phase was analyzed, and di-, piezo- and ferroelectric properties were measured.<br />

The crystal structure changed from tetragonal to<br />

rhombohedral phases in the vicinity <strong>of</strong> morphotropic<br />

phase boundary (MPB) composition with increasing<br />

PMnN. The MPB compositions were almost presumed<br />

to be PMnN/PT/PZ = 1.5-14/43-52/43-46.5, based on<br />

the XRD results. d33, kp and Qm showed maxima (156<br />

pC/N, 34% and 890) at PMnN/PT/PZ = 11/44/45,<br />

respectively. In contrast, Qm showed a tendency to<br />

increase gradually with increasing PMnN content.<br />

Thus, 0.11PMnN-0.44PT-0.45PZ ceramics shows<br />

great promise for piezoelectric actuator applications<br />

because <strong>of</strong> its excellent piezoelectric properties such as<br />

d33 = 157 pC/N, d31 = 51 pC/N, Qm = 695, kp = 34%,<br />

k31 = 20%, ��33 T /��0 = 622, tan δ = 0.52% and Tc =<br />

353 o C.<br />

P- 64<br />

Fig. 1. Variations in (a) d33 and (b)<br />

Qm at room temperature <strong>of</strong> ternary<br />

PMnN-PT-PZ (PMnN/PT/PZ = 4-<br />

14/42-52/44-54) ceramics.


<strong>Poster</strong> session II<br />

Acoustic anomalies and central peaks in 0.83Pb(Mg1/3Nb2/3)O3–0.17PbTiO3<br />

single crystal studied by the micro-Brillouin scattering<br />

Tae Hyun Kim 1,2* , Jae-Hyeon Ko 2 and Seiji Kojima 1<br />

1 PAS, <strong>University</strong> <strong>of</strong> Tsukuba, Tsukuba, Ibaraki 305-8573, Japan<br />

2 Department <strong>of</strong> Physics, Hallym <strong>University</strong>, Chuncheon, Gangwondo 200-702, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : s1130117@u.tsukuba.ac.jp<br />

Dynamic properties <strong>of</strong> relaxor ferroelectric 0.83Pb(Mg1/3Nb2/3)O3–0.17PbTiO3 (PMN-<br />

17PT) single crystals have been studied by miro-Brillouin scattering in a wide temperature<br />

range between 90 and 860 K on both cooling and heating. The Brillouin spectra were<br />

measured by using a tandem Fabry-Perot interferometer combined with an optical microscope.<br />

The temperature dependence <strong>of</strong> Brillouin shift showed the deviation from normal lattice<br />

anharmonicity below the Burns temperature ~ 733 K upon cooling. The observed acoustic<br />

behaviors combined with the central peak dynamics clearly indicated the existence <strong>of</strong><br />

dynamic polar nanoregions (PNRs) in PMN-17PT. This study revealed that longitudinal<br />

acoustic (LA) mode frequency showed a diffuse elastic anomaly upon cooling near the cubicrhombohedral<br />

phase transition temperature (Tc) as well as thermal hysteresis around Tc,<br />

which indicates a typical nature <strong>of</strong> a first order phase transition.<br />

*This research was supported in part by the Marubun Research Promotion Foundation<br />

and Basic Science Research Program through the National Research Foundation <strong>of</strong><br />

Korea(NRF) funded by the Ministry <strong>of</strong> Education, Science and Technology (2010-0010497).<br />

Frequency shift (GHz)<br />

47<br />

46<br />

45<br />

44<br />

43<br />

42<br />

100 200 300 400 500 600 700 800<br />

Temperature (K)<br />

Cooling<br />

Heating<br />

P- 65<br />

FWHM (GHz)<br />

3<br />

2<br />

1<br />

100 200 300 400 500 600 700 800<br />

Temperature (K)<br />

Cooling<br />

Heating<br />

Fig. 1. The temperature dependences <strong>of</strong> the Brillouin frequency shift and the FWHM <strong>of</strong> the LA<br />

mode on both cooling and heating processes.<br />

References<br />

1. S. Kojima and J. -H. Ko, Curr. Appl. Phys. 11 (2011) 522.<br />

2. J. –H. Ko et al., Phys. Rev. B 82 (2010) 104110.


<strong>Poster</strong> session II<br />

Influence <strong>of</strong> tantalum substitution on dielectric, ferroelectric and fieldinduced<br />

strain behavior <strong>of</strong> lead-free 0.99[Bi0.5(Na0.82K0.18)0.5Ti1-xTax)O3]-<br />

0.01LiSbO3 ceramics<br />

A. Zaman 1,2 , A. Hussain 1 , T. K. Song 1 , M. H Kim 1* , Y. Iqbal 2 and W. J. Kim 3<br />

1 School <strong>of</strong> Nano & Advanced Materials Engineering, Chanwon National <strong>University</strong>,<br />

Gyeongnam 641-773, Republic <strong>of</strong> Korea<br />

2 Materials Research laboratory, Institute <strong>of</strong> Physics and Electronics, <strong>University</strong> <strong>of</strong> Peshawar,<br />

Peshawar, Pakistan<br />

3 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Gyeongnam 641-773, Republic <strong>of</strong><br />

Korea<br />

* E-mail address <strong>of</strong> the corresponding author : mhkim@changwon.ac.kr<br />

Lead-free Ta-modified 0.99[(Bi0.82Na18)TiO3-(Bi1/2K1/2)TiO3]-0.01LiSbO3 (BNKTT-LS)<br />

piezoceramics were synthesized by a conventional solid-state reaction method. The effect Ta<br />

addition into the BNKT-LS ceramics was investigated through X-ray diffraction, dielectric,<br />

temperature dependent ferroelectric and field-induced strain characterizations. As the Ta<br />

content was increased, the maximum dielectric constant as well as the depolarization<br />

temperature (Td) decreased. The polarization and strain hysteresis loops indicate that the<br />

addition <strong>of</strong> Ta significantly disrupts the ferroelectric order <strong>of</strong> the BNKT-LS ceramics leading<br />

to a degradation <strong>of</strong> the remanent polarization and coercive field. However, the destabilization<br />

<strong>of</strong> the ferroelectric order is accompanied by a significant enhancement in the unipolar strain.<br />

A large unipolar field-induced strain <strong>of</strong> 0.38% with a normalized (d * 33 = Smax/Emax = 650<br />

pm/V) at a driving field <strong>of</strong> 6 kV/mm was obtained at room temperature for x = 0.013. This<br />

significant strain enhancement is a result <strong>of</strong> the reversible phase transition between a NP<br />

phase in a zero field and a field-induced ferroelectric phase.<br />

P- 66


<strong>Poster</strong> session II<br />

Ferroelectric Properties <strong>of</strong> Potassium Sodium Niobium Oxides Ceramics<br />

with Tetragonal and Orthorhombic Composite Structures<br />

Byeong-Eog Jun 1* , Hyunjun Park 2 , Seongmun Eom 2 ,<br />

Hyunsuk Yoon 2 , Suyeol Lee 2 and Dong Jin Kim 3<br />

1 Department <strong>of</strong> Physics and Earth Science, Korea Science Academy <strong>of</strong> KAIST, Busan 614-<br />

822, Korea<br />

2 Korea Science Academy <strong>of</strong> KAIST, Busan 614-822, Korea<br />

3 Department <strong>of</strong> Physics, Pusan National <strong>University</strong>, Busan 609-735, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : chai2jun@kaist.ac.kr<br />

The alkaline niobates (K,Na,Li)NbO3 ferroelectric ceramics were prepared by applying<br />

liquid phase sintering. For the ferroelectric tetragonal and orthorhombic composite structures<br />

<strong>of</strong> potassium sodium niobium oxides, K1-yNayNbO3 with y = 0.3 (KNN3) and y = 0.7 (KNN7)<br />

perovskite crystalline powders were prepared. In order to prepare the high density composite<br />

ceramics, K3Li2Nb5O15 (KLN) tetragonal tungsten bronze (TTB) crystalline powder was<br />

added to the mix <strong>of</strong> 0.5KNN3+0.5KNN7 perovskite crystalline powders. It is expected that<br />

the KLN TTB crystalline powder results in the liquid phase sintering at the surface boundary<br />

<strong>of</strong> the KNN perovskite crystalline grains during sintering the mixture specimen. KLN TTB<br />

crystalline phase usually modified to the composition <strong>of</strong> K1-yNayNbO3 perovskite grains. It is<br />

considered that the 0.5KNN3+0.5KNN7 composite ceramics showed a mixture <strong>of</strong> tetragonal<br />

and orthorhombic structures. (K,Na,Li)NbO3 composite ceramics were considered to be the<br />

Pe structure with two different K/Na ratios with y = 0.3 and 0.7 in the (1-z)K1-yNayNbO3 +<br />

(z/5)KLN (z = 1, 2, 5 and 10) composite ceramics. We confirmed the ferroelectric tetragonal<br />

and orthorhombic composite structures <strong>of</strong> (K,Na,Li)NbO3 ceramics by using the X-ray<br />

diffraction technique and the ferroelectric D-E loop with the modified Sawyer-Tower circuits.<br />

The dielectric properties were investigated for the unpoled (K,Na,Li)NbO3 composite<br />

ceramics by using the impedance analyzer in the temperature range from room temperature to<br />

600 °C. The possible hybrid effects were considered in order to enhance the piezoelectric<br />

properties <strong>of</strong> the poled (K,Na,Li)NbO3 composite ceramics.<br />

P- 67


<strong>Poster</strong> session II<br />

Composition dependence <strong>of</strong> relaxor properties <strong>of</strong> (1-x)K0.5Na0.5NbO3 –<br />

xBa0.5Ca0.5TiO3 ferroelectric ceramics<br />

C.-W. Cho 1 , M. R. Cha 1 , J. Y. Jang 1 , S. H. Lee 1 , D. J. Kim 1 , J. S. Bae 2 , and S. Park 1*<br />

1 Department <strong>of</strong> Physics, Pusan National <strong>University</strong>, Busan 609-735, Korea<br />

2 Busan Center, Korea Basic Science Institute, Busan 609-735, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : psk@pusan.ac.kr<br />

The Ba0.5Ca0.5TiO3 (BCT) composition dependent structural and dielectric properties <strong>of</strong><br />

(1-x)K0.5Na0.5NbO3 - xBa0.5Ca0.5TiO3 ceramics were investigated. Room temperature x-ray<br />

diffraction revealed that the structure transforms from orthorhombic to cubic with increasing<br />

BCT composition. The shift <strong>of</strong> maximum temperature <strong>of</strong> the maximum dielectric constant at a<br />

particular frequency suggests that the system exhibits ferroelectric relaxor behavior. The<br />

system containing 15 % BCT showed the closest calculated Curie-Weiss exponent to 2, which<br />

the exponent for a relaxor ferroelectric.<br />

Fig. (Left) Inverse dielectric permittivity at 1 MHz as a function <strong>of</strong> temperature for (1-x)KNN-xBCT ceramics<br />

(symbols: experimental data; the solid line: fitting to the Curie-Weiss law). (Right) Log (1/ɛr - 1/ɛmax) at 1 MHz<br />

for (1-x)KNN-xBCT ceramics (symbols: experimental data; solid line: fitting to the modified Curie-Weiss law)<br />

as a function <strong>of</strong> the log (T- Tmax).<br />

P- 68


<strong>Poster</strong> session II<br />

Raman scattering study <strong>of</strong> relaxor ferroelectric Pb(Sc1/2Nb1/2)O3 crystals<br />

Kouhei Suzuki 1* , Haruki Takayama 1 , Muhtar Ahart 2 ,<br />

Alexei A. Bokov 3 , Zuo-Guang Ye 3 and Seiji Kojima 1<br />

1 PAS, <strong>University</strong> <strong>of</strong> Tsukuba, Tsukuba, Ibaraki 305-8573, Japan<br />

2 Geophysical Laboratory, Carnegie Institution <strong>of</strong> Washington, USA<br />

3 Dep. Chem. and 4D LABS, Simon Fraser <strong>University</strong>, Burnaby, BC, V5A 1S6, Canada<br />

* E-mail address <strong>of</strong> the corresponding author : shamo.922@gmail.com<br />

The vibrational properties <strong>of</strong> Pb(Sc1/2Nb1/2)O3 (PSN) relaxor-based ferroelectrics with<br />

perovskite structure have been studied in this work. Polarized and depolarized Raman<br />

scattering have been measured to investigate the ferroelectric phase transitions in slow-cooled<br />

PSN with lead vacancies (PSN-V) and fast-cooled disordered PSN (PSN-DV), and<br />

0.70Pb(Sc1/2Nb1/2)O3-0.30PbTiO3 (PSN-0.3PT) crystals as shown in Fig. 1. The mode<br />

intensity, frequency, and depolarization ratio <strong>of</strong> Raman bands below 400 cm -1 exhibit the<br />

remarkable temperature variation in the vicinity <strong>of</strong> Tm reflecting the change <strong>of</strong> crystal<br />

symmetry. The difference <strong>of</strong> dynamics in the ferroelectric phase transitions among PSN-V,<br />

PSN-DV, and PSN-30PT is discussed on the basis <strong>of</strong> degree <strong>of</strong> order on the B site and lead<br />

vacancies on the A site <strong>of</strong> the perovskite structure.<br />

-100 0 100<br />

Frequency shift (cm<br />

200 300<br />

-1 )<br />

P- 69<br />

PSN-0.3PT<br />

heating<br />

350 o C<br />

220 o 300<br />

C<br />

o C<br />

75 o 180<br />

C<br />

o C<br />

Fig. 1 Temperature dependence <strong>of</strong> Raman scattering spectra.<br />

References<br />

1. Y. Bing, Ph. D Thesis, 2005, Simon Fraser <strong>University</strong>.<br />

2. M. Ahart, A. Hushur, Y. Bing, Z. Ye, R. J. Hemley, and S. Kojima, Appl. Phys. Lett. 94,<br />

142906 (2009).<br />

3. S. Kojima, S. Tsukada, Y. Hidaka, A.A. Bokov, and Z.-G. Ye, J. Appl. Phys. 109, 084114<br />

(2011).


<strong>Poster</strong> session II<br />

Domain structure observations <strong>of</strong> PMN-PT using a second harmonic<br />

generation microscope<br />

Hiroko Yokota 1* , Hokuto Usami 1 and Junichi Kaneshiro 2<br />

1 Department <strong>of</strong> Physics, Chiba <strong>University</strong>, Chiba 263-8522, Japan<br />

2 Laboratory for Comprehensive Bioimaging, RIKEN, Osaka 565-0874, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : yokota@physics.s.chiba-u.ac.jp<br />

(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) is known as a prototype relaxor ferroelectric.<br />

Between 30 and 40% <strong>of</strong> PT concentration, a morphotropic phase boundary (MPB) exists<br />

which separates the PT-rich tetragonal and the PMN-rich rhombohedral phase. Since the<br />

discovery <strong>of</strong> monoclinic phase by Noheda et al., the MPB is regarded as a bridging phase<br />

which connects the tetragonal and rhombohedral phases and it explains a large<br />

piezoelectricity around the MPB region by a polarization rotation model. Recently, a phase<br />

mixture model has been proposed around the MPB region in the case <strong>of</strong> PZT and it is<br />

important to reexamine the domain structure on PMN-PT. To achieve this aim, a second<br />

harmonic generation microscope (SHGM) observation was carried out.<br />

Figure 1 shows the optical system <strong>of</strong> SHG Microscope. To determine a crystal structure<br />

from SHG images, a polarizer and an analyzer were put to change the polar direction <strong>of</strong> a<br />

fundamental and an SH wave. Single crystal PMN-PT30% was used as a specimen. For the<br />

quantitative analysis, a polarizer and an analyzer were rotated with a parallel configuration<br />

and polar plot were obtained as a two dimensional image shown in Fig.2. Three different<br />

patterns can be seen in Fig.2. Based on the domain boundary configuration, the crystal<br />

structure <strong>of</strong> PMN-PT30% was determined as a monoclinic structure. An electric field was<br />

applied and the domain structural analysis will be also discussed.<br />

Fig.1 Optical system <strong>of</strong> SHGM Fig.2 Polarization dependence <strong>of</strong> PMN-PT30%<br />

P- 70


<strong>Poster</strong> session II<br />

Evidence <strong>of</strong> the monoclinic phase around the MPB region in PMN-PT<br />

K. Kurushima 1 , K. Kobayashi 2 , Yoichi Horibe 3 and Shigeo Mori 2,*<br />

1 Toray Research Center, Ohtsu, Shiga 520-8567, Japan<br />

2 Department <strong>of</strong> Materials Science, Osaka Prefecture <strong>University</strong>, Sakai, 599-8531, Japan<br />

3 Rutgers Center for Emergent Materials and Department <strong>of</strong> Physics & Astronomy, Rutgers<br />

<strong>University</strong>, Piscataway, New Jersey 08854, USA.<br />

* E-mail address <strong>of</strong> the corresponding author : mori@mtr.osakafu-u.ac.jp<br />

Piezoelectric materials, which convert electrical energy into mechanical energy, are<br />

important in medical imaging and telecommunication devices [1]. Many studies have been<br />

done in order to understand origin <strong>of</strong> giant piezoelectric response appearing around the<br />

morphotropic phase boundary (MPB) region [2]. Understanding the relationship between the<br />

crystal structures and the giant piezoelectric response is extremely important because x-ray,<br />

electron and neutron diffraction experiments revealed some evidences <strong>of</strong> a monoclinic phase<br />

around MPB [2]. On the other hand, domain structures around MPB has been examined by a<br />

transmission electron microscopic (TEM) and optical methods [3]. In this study,<br />

microstructures around the MPB regions <strong>of</strong> (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 ((1-x)PMNxPT)<br />

were focused on. (1-x)PMN-xPT exhibits the structural phase transition around x~0.3<br />

from the rhombohedral R3m to the tetragonal P4mm phases, as the PT concentration (x)<br />

increases. The boundary between the rhombohedral to the tetragonal structures locates on<br />

x=0.3 and is regarded as the MPB. Here, we carefully investigated the nanoscale domain<br />

structures <strong>of</strong> (1-x)PMN-xPT (x~0.32) by the TEM experiment [4]. Domain structures with<br />

hierarchical inhomogeneities were found in the monoclinic phase near the MPB region at<br />

room temperature. The domain structures are characterized as the nanoscale lamella-type<br />

domain structures with the ~10 nm width inside the large banded domains due to the<br />

tetragonal structures. In addition, we have thoroughly investigated scattering-vector<br />

dependence <strong>of</strong> the domain contrasts by obtaining various dark-field images and determined<br />

orientations <strong>of</strong> the polarization vectors in the nanoscaled lamella-type domain structures and<br />

confirmed the existence <strong>of</strong> the monoclinic structure around the MPB region.<br />

[1] S-E. Park and T. R. Shrout, IEEE trans. Ultrason. Ferroelectr. Freq. Control 4, 1140<br />

(1997).[2] B. Nohed et al., Phys. Rev. B 61, 8687 (2000). Phys. Rev. B 63, 014103 (2000). R.<br />

Schierholz et al., Phys. Rev. B 78, 024118 (2008). R. Guo et al., Phys. Rev. Lett., 84, 5423<br />

(2000). [3] D. Woodward et al., Phys. Rev. B 72 104110 (2005). T. Asada and Y. Koyama,<br />

Phys. Rev. B 75, 214111 (2007).[4] K. Kurushima and S. Mori, Transactions on Ultrasonics,<br />

Ferroelectrics, and Frequency Control (in press), Materials Science and Engineering, 18,<br />

092015 1-1-4 (2011)<br />

P- 71


<strong>Poster</strong> session II<br />

Acoustic phonon behavior in relaxor-based (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3<br />

ferroelectrics studied by Brillouin scattering<br />

Shinya Tsukada 1,2* , Yuki Hidaka 2 , Seiji Kojima 2 , Alexei A. Bokov 3<br />

and Zuo-Guang Ye 3<br />

1 Faculty <strong>of</strong> Education, Shimane <strong>University</strong>, Matsue, Shimane, 609-8504, Japan<br />

2 Pure and Applied Sciences, <strong>University</strong> <strong>of</strong> Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan<br />

3 Dpt. <strong>of</strong> Chemistry, Simon Fraser <strong>University</strong>, Burnaby, British Columbia, V5A 1S6, Canada<br />

* E-mail address <strong>of</strong> the corresponding author : tsukada@edu.shimane-u.ac.jp<br />

The ferroelectric phase transitions in relaxor-based ferroelectric (1-x)Pb(Zn1/3Nb2/3)O3xPbTiO3<br />

(PZN-xPT) crystals, with x = 0.07, 0.10, and 0.12, were investigated using inelastic<br />

light scattering from a longitudinal acoustic (LA) phonon (Fig. 1). An acoustic anomaly in a<br />

broad temperature range, which is a particular property <strong>of</strong> relaxor ferroelectrics[1,2], was<br />

observed, and we described the anomalies in the LA phonon by assuming local piezoelectric<br />

coupling inside polar nanoregions (PNR) which are surrounded by a non-polar matrix. On the<br />

basis <strong>of</strong> local piezoelectric coupling[1,3], a relaxation time � and a dynamic characteristic<br />

length L <strong>of</strong> the order-parameter (polarization) fluctuations were determined to be in the order<br />

<strong>of</strong> 10 -13 s and 10 -9 m, respectively. The �� and L values increase sharply upon cooling from<br />

high temperatures with a more gradual change occurring below the intermediate temperature<br />

T * (~500K). This result implies that rapid growth <strong>of</strong> the polarization fluctuation above T *<br />

becomes mild below T * . The flexion point <strong>of</strong> the growing process in an ergodic relaxor phase<br />

can be related to the characteristic properties <strong>of</strong> relaxor-based solid solutions undergoing a<br />

ferroelectric phase transition.<br />

Intensity<br />

Frequency Shift (GHz)<br />

Cooling 403 K<br />

4<br />

2 LA LA<br />

CP<br />

0<br />

-60 -30 0 30 60<br />

Frequency Shift (GHz)<br />

60<br />

40<br />

20<br />

0<br />

-20<br />

-40<br />

-60<br />

Intensity<br />

Cooling<br />

Cooling 853 K<br />

4<br />

LA LA<br />

0<br />

-60 -30 0 30 60<br />

Frequency Shift (GHz)<br />

200 400 600 800<br />

Temperature (K)<br />

2<br />

0<br />

400.0<br />

800.0<br />

1600<br />

2400<br />

3000<br />

[1] S. Tsukada and S. Kojima, Phys. Rev. B 78, 144106 (2008).<br />

[2] J. H. Ko, D. H. Kim, S. Tsukada, S. Kojima, A. A. Bokov, and Z. G. Ye, Phys. Rev. B 82, 104110<br />

(2010).<br />

[3] S. Tsukada, Y. Hiraki, Y. Akishige, and S. Kojima, Phys. Rev. B 80, 012102 (2009).<br />

P- 72<br />

Figure 1. Contour map <strong>of</strong> inelastic light scattering<br />

intensity from PZN-0.07PT crystal versus<br />

temperature and frequency shift in x(z y+z)x<br />

scattering geometry (FSR = 75 GHz, scan range<br />

= 70.5 GHz). The temperature-dependent<br />

inelastic scattering from the LA phonon is<br />

clearly observed. The dark parts at 0 GHz<br />

denote elastic scattering. The scattering was<br />

measured upon cooling without a polarizer.


<strong>Poster</strong> session II<br />

Ferroelectric-Relaxor Composites in Bi-Based Lead-Free Ceramics<br />

Changhyo Hong, Jin-Kyu Kang, Hyoung-Su Han, Dae-Jun Heo and Jae-Shin Lee *<br />

School <strong>of</strong> Materials and Engineering, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author: jslee@ulsan.ac.kr<br />

Recently, 0.82(Bi1/2Na1/2)TiO3-0.18(Bi1/2K1/2)TiO3 solid solution (BNKT) ceramics<br />

attract great attention because <strong>of</strong> their large electric field-induced strains (EFIS) at<br />

ferroelectric (FE)-nonpolar (NP) boundaries. However, a critical problem that hinders their<br />

practical application to actuators is the fact that large stains in Bi-based lead-free ceramics are<br />

obtained only at high electric fields sufficient to induce a NP-FE phase transition. To lower<br />

the critical field (Ecrit) that can cause the NP-FE phase transition, FE-relaxor (RE) composite<br />

ceramics were investigated in this study. Ceramic-ceramic composites were prepared by<br />

embedding coarse FE BNKT particles in RE Sn-doped BNKT ceramics.<br />

The electric field-induced strain behavior was compared between FE BNKT, RE<br />

BNKT (6 mol% Sn-doped), and FE/RE composites. The normalized strain Smax/Emax <strong>of</strong> the FE<br />

BNKT was 217 pm/V and the RE Sn-doped BNKT was 172 pm/V at 5 kV/mm. However, the<br />

normalized strain <strong>of</strong> FE/RE composites with 30 % FE BNKT was enhanced up to 274 pm/V<br />

at 5 kV/mm. This result indicates that the Ecrit can be lowered by structuring a FE-RE<br />

composite, which is believed to enlighten a new way for finding new lead-free piezoelectric<br />

with large strains.<br />

P- 73


<strong>Poster</strong> session II<br />

Dielectric and Piezoelectric Enhancement <strong>of</strong> New Ceramics with Artificial<br />

MPB Engineering<br />

Ichiro Fujii 1 , Kenta Yamashita 1 , Kouichi Nakashima 1 , Nobuhiro Kumada 1<br />

Satoshi Wada 1* , Chikako Moriyoshi 2 and Yoshihiro Kuroiwa 2<br />

1 Material Science and Technology, Interdisciplinary Graduate School <strong>of</strong> Medical and<br />

Engineering, <strong>University</strong> <strong>of</strong> Yamanashi, 4-4-37 takeda, K<strong>of</strong>u, Yamanashi 400-8510, Japan<br />

2 Department <strong>of</strong> Physical Science, Hiroshima <strong>University</strong>, Higashihiroshima, Hiroshima 739-<br />

8526, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : swada@yamanashi.ac.jp<br />

Barium titanate (BaTiO3, BT) and potassium niobate (KNbO3, KN) (BT-KN) nanostructured<br />

ceramics with artificial morphotropic phase boundary (MPB) structure were<br />

successfully prepared by solvothermal method at temperatures below 230 ˚C. Various<br />

characterizations confirmed that the BT-KN nano-structured ceramics exhibited BT/KN<br />

molar ratio <strong>of</strong> 1, a porosity <strong>of</strong> around 30 % and heteroepitaxial interface between BT and KN.<br />

Their apparent piezoelectric constant d33 * was estimated at 136 pC/N, and was three times<br />

larger value than that <strong>of</strong> the 0.5BT-0.5KN dense ceramics. The concept proposed in this<br />

study can be a new way to create piezoelectric ceramics with artificial MPB region.<br />

Moreover, this method is very universal and applied into various functional materials such as<br />

magnetic, conductive, semi-conductive, and optical materials in addition to dielectric,<br />

piezoelectric and ferroelectric materials. In the future, we will develop various new<br />

materials with heteroepitaxial interfaces on the basis <strong>of</strong> the concept.<br />

P- 74


<strong>Poster</strong> session II<br />

Electrical Properties <strong>of</strong> (Sr0.75,La0.25)TiO3 Ultra-thin Films<br />

Seongtak Yoon 1 , EuiyoungChoi 1 , Yunsang Lee 2 and Jaichan Lee 1*<br />

1 School <strong>of</strong> Advanced Materials Science and Engineering, Sungkyunkwan <strong>University</strong>,<br />

Kyunggido, 440-746, Korea.<br />

2 Department <strong>of</strong> Physics, Soongsil <strong>University</strong>, Seoul, 156-743, Korea.<br />

* E-mail address <strong>of</strong> the corresponding author : jclee@skku.edu<br />

The (Sr0.75, La0.25)TiO3 (SLTO) ultra-thin films with various thicknesses have been<br />

grown on Ti-O terminated SrTiO3 (100) substrate using Laser-Molecular Beam Epitaxy<br />

(Laser MBE). The film structure and topography were verified by atomic force microscopy<br />

(AFM) and high resolution thin film x-ray diffraction by the synchrotron x-ray radiation. We<br />

have also investigated the electronic band structure using x-ray absorption spectroscopy<br />

(XAS). The ultra thin SLTO film exhibited thickness driven metal-insulator transition around<br />

8 unit cell thickness when the film thickness was progressively reduced to 2 unit cell. The<br />

SLTO thin films with an insulating character showed band splitting in Ti L3-L2 edge XAS<br />

spectrum, which is attributed to Ti 3d band splitting. This narrow d band splitting could drive<br />

the metal-insulator transition along with Anderson Localization. In optical conductivity, we<br />

have found the spectral weight transfer from coherent part to incoherent part was observed<br />

when the film thickness was reduced. This result indicates the possibility <strong>of</strong> enhanced<br />

electron correlation in ultra thin films.<br />

P- 75


<strong>Poster</strong> session II<br />

Transport Properties <strong>of</strong> Low Dimensional La0.75Sr0.25VO3 Thin Films<br />

Taejun Hwang 1 , Tran Minh Dao 1 , Partha S. Mondal 1 and Jaichan Lee 1*<br />

1 School <strong>of</strong> Advanced Materials Science and Engineering, Sungkyunkwan <strong>University</strong>,<br />

Kyunggido, 440-746, Korea.<br />

* E-mail address <strong>of</strong> the corresponding author : jclee@skku.edu<br />

The La0.75Sr0.25VO3 (LSVO) ultra-thin epitaxial films with various thicknesses (5 to 25<br />

uc) were deposited on atomically flat (001) oriented LaAlO3 (LAO) substrate by pulsed laser<br />

deposition. LSVO films with thickness larger than 8 uc exhibited metallic behavior and<br />

underwent a metal-insulator transition (MIT) at thicknesses between 8 uc and 5 uc. Above the<br />

critical thickness <strong>of</strong> 5 unit cell, metallic films exhibit a temperature driven metal-insulator<br />

transition with weak localization behavior while LSVO with the nominal composition<br />

exhibits correlated metal behavior. With decreasing film thickness, oxygen octahedron<br />

rotation in the films increases, causing enhanced electron-electron correlation. The observed<br />

MIT is attributed to early onset <strong>of</strong> electron-electron correlation, i.e., bandwidth narrowing<br />

driven by the splitting <strong>of</strong> V 3d t2g band in low dimensional structures as well as Anderson<br />

localization represented by the disorder parameter approaching to the I<strong>of</strong>fe-Regel limit.<br />

P- 76


<strong>Poster</strong> session II<br />

Structural study <strong>of</strong> gradient lattice distortion in BaTiO3-KNbO3 composites<br />

with heteroepitaxial interface<br />

Eisuke Magome 1* , Yoshihiro Kuroiwa 1 , Hironori Yoshimura 1 , Chikako Moriyoshi 1 ,<br />

Kenta Yamashita 2 , Ichiro Fujii 2 , Kouichi Nakashima 2 ,<br />

Nobuhiro Kumada 3 and Satoshi Wada 2<br />

1 Graduate School <strong>of</strong> Science, Hiroshima <strong>University</strong>, Hiroshima 739-8526, Japan<br />

2 Interdisciplinary Graduate School <strong>of</strong> Medical and Engineering, <strong>University</strong> <strong>of</strong> Yamanashi,<br />

Yamanashi 400-8510, Japan<br />

3 Center for Crystal Science and Technology, <strong>University</strong> <strong>of</strong> Yamanashi, Yamanashi 400-8511,<br />

Japan<br />

* E-mail address <strong>of</strong> the corresponding author : magome@sci.hiroshima-u.ac.jp<br />

Lead-free ferroelectric materials are <strong>of</strong> concern due to the environmental problems, and<br />

are anticipated to be substituted for conventional ferroelectrics such as Pb(Zr,Ti)O3 ceramics.<br />

Recently, we have found that solvothermally synthesized BaTiO3 (BT)-KNbO3 (KN)<br />

composites with a heteroepitaxial interface show the fairly large piezoelectric constant<br />

compared with sintered BT-KN composites in the normal way [1]. The enhancement in the<br />

piezoelectric response would be attributed to the distinct interface, so that we consider that<br />

promising lead-free ferroelectric materials are emerged in the process to develop such<br />

composites with a heteroepitaxial interface. In this study, we have carried out the structural<br />

study <strong>of</strong> the KN-BT composites to reveal the clear relationships between the crystal structures<br />

<strong>of</strong> the interface and the dielectric property.<br />

KN-BT composites with the KN/BT molar ratio <strong>of</strong> 0.5 were synthesized by solvothermal<br />

method, in which the ceramic grain with homogeneous size-distribution is configurated with a<br />

BT particle with a radius <strong>of</strong> 150 nm at the inner core covered with KN. Synchrotron radiation<br />

powder diffraction data were collected using the large Debye-Scherrer camera installed at<br />

SPring-8 BL02B2. The energy <strong>of</strong> X-rays was 18.5 keV (wave length ��= 0.669 Å). We<br />

analyzed the crystal structure <strong>of</strong> the ceramic grain on the basis <strong>of</strong> the core/multi-shell model<br />

using the Rietveld method. It is revealed that the BT particle is significantly distorted in the<br />

large region to form the interface with KN through the gradually distorted region from the<br />

tetragonal structure at the core toward the cubic structure at the boundary between BT and<br />

KN. The volume <strong>of</strong> the distorted interface region is decreased and the piezoelectric response<br />

is suppressed by annealing the composites at 1000ºC for 10 h. These experimental results<br />

provide an evidence that the interface controls the ferroelectric properties <strong>of</strong> the composite<br />

ceramics.<br />

[1] I. Fujii et al. : Appl. Phys. Lett. 99 (2011) 202902.<br />

P- 77


<strong>Poster</strong> session II<br />

Characterization <strong>of</strong> BN doped BaTiO3 PTC thermister<br />

Myoung Pyo Chun * and Sung Kyoung Hong<br />

Korea Institute <strong>of</strong> Ceramic Engineering & Technology(KICET), Seoul 153-801, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : myoungpyo@kicet.re.kr<br />

PTC thermister has been used as an over-current protector which is connected in series<br />

with the circuit <strong>of</strong> electrical devices. So, it is required that PTC thermister has low resistance<br />

at room temperature. BN doped (Ba0.998Sm0.002)TiO3 PTC thermisters (BN=0.02, 0.025, 0.03<br />

mol) were synthesized by the solid state method and their disk samples <strong>of</strong> diameter 0.5mm<br />

were prepared by firing at 1040 and 1060 o C in reduced atmosphere <strong>of</strong> 10%H2-90%N2 gas.<br />

The electrical properties and the microstructure <strong>of</strong> the disk samples were obtained with the<br />

impedance analyzer and SEM. With increasing BN content in (Ba0.998Sm0.002)TiO3, the<br />

resistance at room temperature increases continuously, which seems to be related with the<br />

thickness <strong>of</strong> BN-insulation layer at the grain boundary. The behavior <strong>of</strong> the resistance at room<br />

temperature <strong>of</strong> the disk samples as a function <strong>of</strong> BN content in (Ba0.998Sm0.002)TiO3 PTC<br />

thermister was investigated with Cole-Cole plot.<br />

P- 78


<strong>Poster</strong> session II<br />

Grain growth and piezoelectric property <strong>of</strong> (Na0.545K0.47)(Nb0.55Ta0.45)O3<br />

with a sintering aid <strong>of</strong> Li2CO3 and MnO2 by template grain growth method<br />

Da Jeong Kim 1 , Myang Hwan Lee 1 , Jin Su Park 1 , Dalhyun Do 1 , Myong-Ho Kim 1 ,<br />

Sang Wook Kim 2 , Hae In Choi 2 , Sang Su Kim 2 , Won Jeong Kim 2<br />

and Tae Kwon Song 1*<br />

1 School <strong>of</strong> Nano and Advanced Material Engineering, Changwon National <strong>University</strong>,<br />

Changwon 641-773, Korea<br />

2 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : tksong@changwon.ac.kr<br />

Lead-free piezoelectric materials, K0.5Na0.5NbO3 (KNN) based ceramics, have been<br />

carried out to improve the sinterability and piezoelectric properties. The addition <strong>of</strong> Li2CO3<br />

and MnO2 as a sintering aid was found to improve the densification <strong>of</strong> ceramics and decrease<br />

the sintering temperature <strong>of</strong> the ceramics.<br />

In this poster, we investigated the addition <strong>of</strong> (Na0.545K0.47)(Nb0.55Ta0.45)O3 (NKNT)<br />

piezoelectric ceramics with Li2CO3 and MnO2 sintering aid fabricated by a tape casting<br />

method using a plate-like NaNbO3 particle. The microstructures and phase formation <strong>of</strong> the<br />

textured NKNT thick films were investigated by a scanning electron microscopy and an X-ray<br />

diffractometer, respectively. Within 2� = 20 o - 60 o , the orientation degree (F, Lotgering<br />

factor) was calculated by a Lotgering method. Piezoelectric constant (d33) and dielectric<br />

constants were measured with piezo d33 meter and an impedance analyzer, respectively.<br />

P- 79


<strong>Poster</strong> session II<br />

Structural analysis <strong>of</strong> lead free (Bi0.5Na0.5)TiO3 base ceramics<br />

using Rietveld refinement method<br />

Sang Wook Kim 1 , Hae In Choi 1 , Myang Hwan Lee 2 , Dalhyun Do 2 , Jin Su Park 2 ,<br />

Da Jeong Kim 2 , Tae Kwon Song 2 , Myong Ho Kim 2 , Sang Su Kim 1<br />

and Won Jeong Kim 1*<br />

1 Department <strong>of</strong> Physics, Changwon National <strong>University</strong>, Changwon 641-773, Korea<br />

2 School <strong>of</strong> Nano & Advanced Materials Engineering, Changwon National <strong>University</strong>,<br />

Changwon, Gyeongnam 641-773, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kwj@changwon.ac.kr<br />

Lead-based piezoelectric ceramics with a perovskite, such as Pb(Zr,Ti)O3, are widely<br />

used for actuators, sensors and microelectronic devices because <strong>of</strong> their excellent<br />

piezoelectric properties. However, the toxicity <strong>of</strong> lead and its high vapor pressure during<br />

processing have led to a demand for alternative lead-free piezoelectric materials that are<br />

environmentally benign from the viewpoint <strong>of</strong> sustainable development. The (Bi0.5Na0.5)TiO3<br />

(BNT) materials have been developed as a promising lead-free piezoelectric material for<br />

environmentally benign good piezoelectric devices.<br />

In this study, the BNT-based ceramics were formed using a solid state reaction method.<br />

Structure <strong>of</strong> the BNT-based ceramics was analyzed by a Rietveld refinement with X-ray<br />

diffraction data. The result was compared to that <strong>of</strong> the Cohen’s method. More detailed fitting<br />

procedures and results will be discussed in the presentation.<br />

P- 80


<strong>Poster</strong> session II<br />

Lithium doping in the Gallium and Magnesium modified Zinc Oxides<br />

Byeong-Eog Jun 1 , Dongwon Jang 2 , Sungwon Ha 2 , DongHyuk Choi 2 , Hui Jung 2<br />

and Byung Chun Choi 3*<br />

1 Department <strong>of</strong> Physics and Earth Science, Korea Science Academy <strong>of</strong> KAIST,<br />

Busan 614-822, Korea<br />

2 Korea Science Academy <strong>of</strong> KAIST, Busan 614-822, Korea<br />

3 Department <strong>of</strong> Physics, Pukyong National <strong>University</strong>, Busan 608-737, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : bcchoi@pknu.ac.kr<br />

The Li-doped modified zinc oxide Zn1-xMexO:Li (Me = Ga, Mg) ceramics were studied<br />

for the transparent conductive oxide thin films on Al2O3 (0001) substrate. The Li doping was<br />

considered for the modified ZnO to show a p-type semi-conductive properties by using the<br />

Zn1-xMexO:Li ceramics targets with Li contents <strong>of</strong> 0.05 at%, and 0.10 at%. Where, the Ga<br />

modification was confirmed to contribute to the n-type conductivity <strong>of</strong> Zn1-xGaxO:Li<br />

(ZGO:Li) thin films. Li content may contribute to increase the electron mobility in the<br />

ZGO:Li thin films when compared to the ZGO thin films. We also consider that Li doping in<br />

the Zn1-xMgxO (ZMO:Li) ceramics. Where, x ranges from 0 to 0.5 while maintaining Li<br />

contents <strong>of</strong> 0.5 at% and 0.1 at%. ZMO:Li ceramics were characterized by using the X-ray<br />

diffraction, the scanning electron microscopy. We investigate the preparations <strong>of</strong> ZGO:Li and<br />

ZMO:Li target ceramics for the pulsed laser deposition or DC magnetron sputtering<br />

techniques. The main issue is about the p-type conduction by doping Li in the ZGO and ZMO<br />

host materials. Usually, Ga 2+ ion in the Zn site contribute negative excess charges while Mg 2+<br />

ions show a neutral substitution for Zn sites. Therefore, we expect that Li doping may<br />

contribute to the p-type conduction in the ZMO host materials. Although we considered the Li<br />

doping is a minor contribution to the ZGO host material, the extrinsic contribution to the ntype<br />

conduction is expected at the grain boundary in the ZGO:Li thin films.<br />

P- 81


<strong>Poster</strong> session II<br />

Low-Temperature Synthesis <strong>of</strong> (Na,K)NbO3 by Dissolution-Precipitation<br />

Method<br />

Kengo Shibata, Seiji Yamazoe* and Takahiro Wada<br />

Department <strong>of</strong> Materials Chemistry, Ryukoku <strong>University</strong>, Otsu 520-2194, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : yamazoe@rins.ryukoku.ac.jp<br />

Low-temperature synthesis <strong>of</strong> (Na,K)NbO3 (NKN) attracts much attention in the leadfree<br />

ferroelectric field. Some low temperature synthesis methods were reported, such as solgel<br />

method and hydrothermal method. However, these synthesis methods have some<br />

restrictions such as expensive raw materials and high-pressure vessel. In the present study, we<br />

provide a new low-temperature synthesis method <strong>of</strong> NKN by a simple dissolutionprecipitation<br />

method. We found that the morphology <strong>of</strong> the NKN crystals could be controlled<br />

by this method.<br />

First, we synthesized Na3NbO4 precursor from Nb2O5, Na2C2O4 and (NH2)2CO by a<br />

modified solid solution method at 800<br />

Fig.1 SEM micrographs <strong>of</strong><br />

(a) Na7(H3O)Nb6O19 ·14H2O<br />

intermediate crystals,and<br />

(b) (Na0.5K0.5)8Nb6O19·9H2O<br />

intermediate crystals.<br />

o C. The Na3NbO4 precursor was dissolved in aqueous<br />

buffer solutions <strong>of</strong> pH = 7 (KCl + HCl). The pH <strong>of</strong> the solution was increased by the addition<br />

<strong>of</strong> NaOH and/or KOH solution. When the pH <strong>of</strong> the solution increased up to pH = 13, white<br />

powder was precipitated. The obtained white powder was separated by filtration and dried at<br />

100 o C for 10 min. Then, the dried powder was heated at 500 o C for 4 h in air. The obtained<br />

sample was analyzed by powder X-ray diffraction (XRD) and scanning electron microscope<br />

(SEM).<br />

XRD analysis showed that the white powders<br />

obtained using NaOH and using NaOH: KOH = 1: 1<br />

solution are Na7(H3O)Nb6O19·14H2O and<br />

(Na0.5K0.5)8Nb6O19·9H2O, respectively. Figures 1 (a) and<br />

(b) show the SEM images <strong>of</strong> Na7(H3O)Nb6O19·14H2O and<br />

(Na0.5K0.5)8Nb6O19·9H2O crystals, respectively. The<br />

Na7(H3O)Nb6O19·14H2O crystals have needle-like and the<br />

(Na0.5K0.5)8Nb6O19·9H2O crystals have plate-like<br />

morphologies. This result showed that the Na/K ratio <strong>of</strong><br />

the solution is important for controlling the composition<br />

and morphology <strong>of</strong> crystals. We confirmed that needlelike<br />

NaNbO3 and plate-like (Na0.5K0.5)NbO3 are obtained<br />

by heating needle-like Na7(H3O)Nb6O19·14H2O and platelike<br />

(Na0.5K0.5)8Nb6O19·9H2O, respectively.<br />

P- 82


<strong>Poster</strong> session II<br />

O2 Annealing Effect on KF-Substituted BaTiO3 Ceramics<br />

Masahiko Bekki 1* , Junnya Ikeda 2 , Shinya Tsukada 1,2 and Yukikuni Akishige 1,2<br />

1 Graduate school <strong>of</strong> Education, Shimane <strong>University</strong>, Matsue city, Shimane 609-8504 , Japan<br />

2 Faculty <strong>of</strong> Education, Shimane <strong>University</strong>, Matsue city, Shimane 690-8504, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : E129209@matsu.shimane-u.ac.jp<br />

Recent concern over the environment requires the development <strong>of</strong> lead-free piezoelectric<br />

materials. We have reported that lead-free KF-substituted BaTiO3 (Ba1-xKxTiO3-xFx: KF-BT/x)<br />

single crystals with x~ 0.10 show favorable piezoelectric and dielectric properties (d33 ~ 300<br />

pC/N, �’~ 10000 at room temperature) [1, 2]. In the present stage, it is interesting to fabricate<br />

ceramic forms <strong>of</strong> KF-BT/x. As we reported that F in KF-BT/x evaporates easily and changes<br />

the properties [3], it is necessary to avoid the evaporation <strong>of</strong> F. So we prepared the ceramics<br />

by Spark Plasma Sintering (SPS) method which can sinter ceramics in a short time (~ 10 min)<br />

with fast heating/cooling rates [4]. However, ceramics after sintering by SPS method needs<br />

annealing to compensate vacancies, and the annealing process results in adverse effect. In the<br />

present study, we investigate appropriate annealing condition to fabricate high quality KF-<br />

BT/0.10 ceramics.<br />

TC, a benchmark how much F evaporates [3], <strong>of</strong><br />

KF substitution ratio : x<br />

each KF-BT/0.10 ceramics after annealing was 0.1 0.09 0.08 0.07 0.06<br />

400<br />

determined by dielectric measurement and is shown in<br />

Fig. 1. TC increases as annealing temperature (TA)<br />

350<br />

increases, which is consistent <strong>of</strong> the result <strong>of</strong> single<br />

crystals. This result indicates that annealing at TA~<br />

300<br />

1073 K is the most favorable for KF-BT/0.10<br />

ceramics from a standpoint <strong>of</strong> TC. If we assume that<br />

250<br />

change in TC is all attributed to the evaporation <strong>of</strong> F,<br />

1100 1200 1300 1400<br />

TA (K)<br />

the amount <strong>of</strong> evaporation is expressed by the solid<br />

Figure 1.T vs. T C A (bottom), x (upper)<br />

line in Fig. 1 where the solid line was obtained from <strong>of</strong> KF-BT/0.10. The solid line is<br />

the x dependences <strong>of</strong> TC in single crystals [2].<br />

obtained from Ref. 2.<br />

[1] Y. Akishige : J. Phys. Soc. Jpn. 75 (2006) 073704.<br />

[2] Y. Akishige : Ferroelectrics 369 (2008) 91.<br />

[3] S. Tsukada and Y. Akishige : Scripta Mater. 64 (2011) 268.<br />

[4] Y. Akishige, K. Honda, and S. Tsukada : Jpn. J. Appl. Phys. 49 (2010) 09MC03.<br />

P- 83<br />

TC (K)


<strong>Poster</strong> session II<br />

Crystal structures and polarization/piezoelectric properties <strong>of</strong> ferroelectric<br />

(Bi0.5K0.5)TiO3–(Bi0.5Na0.5)TiO3 Single Crystals<br />

Ken Yanai 1 , Akifumi Morishita 1 , Yuuki Kitanaka 1 , Yuji Noguchi 1* ,<br />

Masaru Miyayama 1 , Chikako Moriyoshi 2 , Yoshihiro Kuroiwa 2 , Shuki Torii 3<br />

and Takashi Kamiyama 3<br />

1 RCAST, The <strong>University</strong> <strong>of</strong> Tokyo, Tokyo 153-8904, Japan<br />

2 Department <strong>of</strong> Physical Science, Hiroshima <strong>University</strong>, Hiroshima 739-8526, Japan<br />

3 High Energy Accelerator Research Organization, Ibaraki 319-1106, Japan<br />

* E-mail address <strong>of</strong> the corresponding author : ynoguchi@crm.rcast.u-tokyo.ac.jp<br />

Bi-based ferroelectric perovskites have attracted a great deal <strong>of</strong> attention from scientific<br />

and technological points <strong>of</strong> view. Considerable efforts have been devoted to developing highperformance<br />

piezoelectric ceramics for e.g. the x(Bi0.5K0.5)TiO3–(1−x)(Bi0.5Na0.5)TiO3<br />

[xBKT–BNT] system 1), 2) but there are few reports on single crystals <strong>of</strong> xBKT–BNT,<br />

probably because <strong>of</strong> technical difficulty in growing crystals due to high vapor pressures <strong>of</strong> Bi<br />

and K at high temperatures. In this study, high-quality single crystals <strong>of</strong> xBKT–BNT were<br />

grown by the high-oxygen pressure top-seeded solution<br />

growth method, 5) and the polarization and piezoelectric<br />

properties were investigated. The crystal structures were<br />

analyzed by single crystal synchrotron x-ray diffraction<br />

(XRD) obtained at SPring-8 BL02B1 and high-resolution<br />

neutron powder diffraction (NPD) measured by<br />

SuperHRPD at KEK.<br />

Figure 1 shows the lattice parameters and<br />

tetragonalities (c/a) <strong>of</strong> xBKT–BNT refined by the NPD<br />

Rietveld analysis. The following phase diagram for the<br />

xBKT–BNT system (unpoled, i.e., without electric field) is<br />

proposed : x = 0–0.20 ; rhombohedral (R3c, R) , x = 0.30–1.0 ;<br />

tetragonal (P4mm, T), x = 0.20–0.30 ; the mixture (R and T) <strong>of</strong><br />

R3c and P4mm. Single-crystal XRD analysis confirmed the<br />

phase diagram shown in Fig .1.<br />

Figure 2 shows the in-situ XRD spots for 0.48BKT–BNT<br />

crystals under applying electric fields : (a) E = 0 kV/cm (after<br />

poled at E = −60 kV/cm), (b) E = +30 kV/cm, (c) E<br />

= +80 kV/cm. The dynamics <strong>of</strong> 90-deg domains<br />

were clearly revealed as follows: I. main 412 and<br />

sub 124 spots due to the presence <strong>of</strong> 90-deg<br />

domains were observed; II. polarization switching<br />

was accomplished through the rotation <strong>of</strong> 90-deg<br />

domains ; III. the 90-deg domain rotation was<br />

induced below coercive field EC (40 kV/cm).<br />

1) Y. Hiruma et al., J. Appl. Phys., 103, 084121<br />

(2008). 2) K.Yoshiiet al., Jpn. J. Appl. Phys.,45(5B), 4493-4496 (2006). 3) A. Morishita et al.,<br />

J. Adv. Dielectr., 1, 63–69, (2011). 4) R. Sun et al., J. Appl. Phys., 109, 124113 (2011). 5)Y.<br />

Kitanaka et al., Ferroelectrics, 414, 24 (2011).<br />

P- 84<br />

3), 4)<br />

Fig.1. Lattice parameters and<br />

tetragonalities and a phase diagram<br />

<strong>of</strong> xBKT–BNT.<br />

Fig. 2. P-Ehysteresisloop and in-situ x-ray<br />

diffraction patternsunder applying various<br />

electric fields <strong>of</strong> 0.48BKT–BNTsingle<br />

crystals.


<strong>Poster</strong> session II<br />

Density functional theory study <strong>of</strong> paraelectric-ferroelectric phase<br />

transition <strong>of</strong> polyvinylidene difluoride<br />

Won-June Kim 1 , Won Joon Heo 1 , Myunghoon Han 1 , Young-Han Shin 2<br />

and Eok Kyun Lee 1*<br />

1 Department <strong>of</strong> Chemistry, Korea Advanced Institute <strong>of</strong> Science and Technology, Daejeon<br />

305-701, Korea<br />

2 Department <strong>of</strong> Physics and Chemistry and EHSRC, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749,<br />

Korea<br />

* E-mail address <strong>of</strong> the corresponding author : eklee@kaist.ac.kr<br />

Since the well-known ferroelectric Pb(Zr,Ti)O3 (PZT) is environmentally hazardous due<br />

to the toxic element Pb, lead-free inorganic ferroelectric perovskites such as BiFeO3 and<br />

(K,Na)NbO3 and organic ferroelectrics such as polyvinyledene difluoride (PVDF) have been<br />

suggested as promising candidates for future ferroelectric and piezoelectric materials. Even<br />

though PVDF shows worse ferroelectric and piezoelectric properties than PZT, it has been<br />

used in many applications thanks to its high flexibility and lightness. Among the five phases<br />

(α, β, γ, δ and ε phases) <strong>of</strong> PVDF, the paraelectric α phase and the ferroelectric β phase are the<br />

main interesting phases. The β phase can be synthesized from α phase by mechanical drawing<br />

and electrical poling, but the mechanism for this transition has not been fully understood yet.<br />

Some theoretical studies on α-β phase transition have been carried out using unit cell model,<br />

but these models cannot account for the nucleation and propagation in a polymeric chain. In<br />

our study, therefore, we firstly perform static density functional theory calculations to observe<br />

the total energy <strong>of</strong> each α and β phases as a function <strong>of</strong> the lattice parameters in the<br />

orthorhombic structure. The energy barrier between the two phases is roughly estimated to be<br />

about 0.1 eV per PVDF monomer (C2H2F2). Identifying the reaction path connecting the<br />

ground states <strong>of</strong> the α and β phases and the estimated transition state, we confirm that<br />

mechanical drawing along the PVDF chain axis is essential for the α-β phase transition.<br />

Secondly, we perform ab-initio molecular dynamics (AIMD) and nudged elastic band (NEB)<br />

simulations for the single-chain PVDF to understand the aperiodic dynamics <strong>of</strong> the α-β phase<br />

change. From the Fourier analysis <strong>of</strong> the time series <strong>of</strong> polarization, we find that the phonon<br />

modes corresponding to dihedral angles change during the phase transition.<br />

P- 85


<strong>Poster</strong> session II<br />

First-principles study <strong>of</strong> piezoelectric and dielectric properties <strong>of</strong> a<br />

graphene-based dipolar layer<br />

Hye-Jung Kim and Young-Han Shin *<br />

Department <strong>of</strong> Physics and EHSRC, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : hoponpop@ulsan.ac.kr<br />

By selectively controlling hydrogenation and fluorination <strong>of</strong> graphene, the inversion<br />

symmetry <strong>of</strong> a graphene layer can be broken. It allows induction <strong>of</strong> the spontaneous<br />

polarization or piezoelectric properties [1]. For the hydrogenated and fluorinated graphene<br />

(C2HF), which hydrogen atoms are attached from the top <strong>of</strong> a graphene layer and fluorine<br />

atoms from the bottom <strong>of</strong> the layer in an ideal condition, four different C2HF conformations<br />

are generated by attached atoms, which are referred to as chair, boat, zigzag, and armchair<br />

conformations. We examine the stability <strong>of</strong> these C2HF conformations by calculating the<br />

formation energies <strong>of</strong> them, and confirm that the four conformations are energetically stable<br />

and the chair conformation is the most stable <strong>of</strong> them all. For the chair C2HF layer, the<br />

spontaneous polarization PS along the direction perpendicular to the layer is computed as 47.3<br />

pC/m in terms <strong>of</strong> the Berry phase calculation [2]. In order to investigate the possibility <strong>of</strong> this<br />

C2HF layer structure in device applications, we propose a simple structure that a chair C2HF<br />

layer is inserted between two graphene single layers, and study the characteristic changes in<br />

structural and electronic properties. All calculations have been performed within densityfunctional<br />

theory (DFT) formalism.<br />

[1] M.T. Ong, and E.J. Reed, ACS Nano 6, 1387 (2011).<br />

[2] R.W. Nunes, and X. Gonze, Phys. Rev. B 63, 155107 (2001).<br />

P- 86


<strong>Poster</strong> session II<br />

Piezoelectricity and elasticity <strong>of</strong> hydrogenated boron nitride monolayer<br />

Md. Noor-A-Alam, Hye Jung Kim and Young-Han Shin *<br />

Department <strong>of</strong> Physics, <strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, <strong>Ulsan</strong> 680-749, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : hoponpop@ulsan.ac.kr<br />

Having been noncentrosymmetric, a hexagonal boron nitride monolayer, in contrast to<br />

graphene, is a piezoelectric. But it shows neither in-plane nor out-<strong>of</strong>-plane dipole moment due<br />

to its complete flatness and three fold symmetry on the plane [1]. However, hydrogenation<br />

distorts the flatness and introduces out-<strong>of</strong>-plane dipole moment for chair form <strong>of</strong><br />

hydrogenated boron nitride, while boat form has no out-<strong>of</strong>-plane dipole due to its atoms’<br />

position in the unit cell. Consequently chair form <strong>of</strong> hydrogenated boron nitride monolayer<br />

shows both in-plane and out-<strong>of</strong>-plane piezoelectric responses while pristine hexagonal boron<br />

nitride monolayer has only an in-plane piezoelectric response. For a two-dimensional<br />

hydrogenated boron nitride monolayer with trigonal (3m) symmetry, there is a vacuum region<br />

along the direction perpendicular to the sheet (the z-direction), so nonzero piezoelectric stress<br />

coefficients are e31, e32, e11, e12, and e26 in voigt notation where e31=e32 and e11=-e12=-1/2e26.<br />

The same symmetry analysis holds for the piezoelectric strain coefficients (dij). In this work,<br />

we compute independent piezoelectric coefficients (e11, e31, d11, and d31) for the chair form <strong>of</strong><br />

hydrogenated boron nitride by using the density functional theory calculations, and find that<br />

our piezoelectric response is quite comparable with PVDF and its copolymers, and also with<br />

recently discovered engineered piezoelectric graphene [2]. We also calculate the independent<br />

elastic stiffness constants (C11 and C12) for the two-dimensional hydrogenated boron nitride<br />

monolayer and observe that hydrogenation, because <strong>of</strong> the change in hybridization <strong>of</strong> boron<br />

and nitrogen atoms, lowers the stiffness <strong>of</strong> the sheet. Such a piezoelectric two-dimensional<br />

hydrogenated boron nitride monolayer can be a candidate material for various nanoelectromechanical<br />

applications.<br />

[1] Na Sai and E. J. Mele, Phys. Rev. B 68, 241405(R) (2003).<br />

[2] M.T. Ong, and E.J. Reed, ACS Nano 6, 1387 (2012).<br />

P- 87


<strong>Poster</strong> session II<br />

Atomic displacement <strong>of</strong> Tetragonal PbTiO3 with different<br />

high electric field directions<br />

Gantsooj Amarsanaa and Ill Won Kim*<br />

Department <strong>of</strong> Physics and Energy Harvest-Storage Research Center,<br />

<strong>University</strong> <strong>of</strong> <strong>Ulsan</strong>, 680-749, <strong>Ulsan</strong>, South Korea<br />

* E-mail address <strong>of</strong> the corresponding author : kimiw@mail.ulsan.ac.kr<br />

Recently, piezoelectric response <strong>of</strong> epitaxial constrained Pb(Zr0.2Ti0.8)O3 thin films using<br />

novel approach in which dielectric breakdown was avoided by using ultra-short pulse <strong>of</strong><br />

electric field. This allowed access too much larger electric fields than previous possible, up to<br />

about 500 MV/m compared with ~50 MV/m studied in earlier experiments. We displaced Ti<br />

atom slightly 0.01 alone z axis in reduced coordinate after several interaction cubic PbTiO3<br />

transfer to tetragonal PbTiO3. The dependence <strong>of</strong> atomic displacements is almost linear range<br />

up to 500 MV/m in electric field directed to tetragonal axis in the reduced coordinate. In this<br />

work, we calculated the atomic displacements <strong>of</strong> ferroelectric PbTiO3 by using the first<br />

principle method and also investigated high electric field to tetragonal PbTiO3 at different<br />

directions <strong>of</strong> electric field using Berry phase method and ABINIT package.<br />

P- 88


<strong>Poster</strong> session II<br />

Energy-band alignment and orbital-selective charge transfer at oxygendeficient<br />

LaAlO3/SrTiO3(001) interfaces<br />

P. V. Ong 1 and Jaichan Lee 1*<br />

1 School <strong>of</strong> Advanced Materials Science & Engineering, Sungkyunkwan <strong>University</strong>,<br />

Suwon, 440-746, Korea<br />

* E-mail address <strong>of</strong> the corresponding author : jclee@skku.edu<br />

Density-functional theory (DFT) within the local density approximation (LDA) +<br />

Hubbard U and the Heyd-Scuseria-Ernzerh<strong>of</strong> (HSE06) hybrid functional approaches were<br />

used to study the energy-band alignment and electronic states in stoichiometric and oxygendeficient<br />

LaAlO3/SrTiO3 superlattices with regularly spaced n-type and p-type interfaces. We<br />

found that the band alignments at the interfaces <strong>of</strong> the LAO/STO superlattices are <strong>of</strong> type II<br />

band lineups with small valence-band <strong>of</strong>fsets. Fundamental asymmetric behaviors between<br />

the complementary n-type and p-type interfaces were revealed. Oxygen vacancies are more<br />

electrostatically favorable at the p-type interface than at the n-type one. The extra electrons<br />

induced by the oxygen vacancies at the p-type interface strongly spread to the n-type interface<br />

and occupy the Ti 3d xy orbitals, while those induced by the vacancies at the n-type interface<br />

are strictly confined and reside in Ti<br />

3d 2 2 and/or 3 2 2<br />

x � y<br />

z r<br />

P- 89<br />

d 3 �<br />

orbtials. Implications and<br />

applications <strong>of</strong> the results on the LaAlO3/SrTiO3 multilayers and heterostructures with single<br />

n- or p-type interface are discussed in detail.


<strong>Poster</strong> session II<br />

Ferroelectric phase transition <strong>of</strong> AgNbO3: a first-principles study<br />

Hiroki Moriwake 1,* , Craig A. J. Fisher 1 , Akihide Kuwabara 1 and Desheng Fu 2<br />

1 Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya, JAPAN<br />

2 Shizuoka <strong>University</strong>, Hamamatsu, JAPAN<br />

* E-mail address <strong>of</strong> the corresponding author : moriwake@jfcc.or.jp<br />

AgNbO3 exhibits an anti-ferroelectric phase transition to an orthorhombic Pbcm phase at<br />

around 340 K. Recently, Fu et al. 1 reported on the ferroelectric behavior <strong>of</strong> this compound.<br />

However, its ferroelectric structure is still not well understood. Levin et al. 2 reported the<br />

ferroelectric phase <strong>of</strong> AgNbO3 to also have Pbcm symmetry, attributing its ferroelectricity to<br />

local symmetry breaking and/or a defective structure. More recently, Yashima et al. 3<br />

proposed space group Pmc21 for the ferroelectric phase based on converged beam electron<br />

diffraction and neutron and X-ray diffraction results. Here we report first-principles<br />

calculations <strong>of</strong> the ferroelectric phase <strong>of</strong> AgNbO3 using the projector augmented wave<br />

method based on density<br />

functional theory. The<br />

calculated phonon<br />

dispersion curve <strong>of</strong> the<br />

room temperature Pbcm<br />

phase is shown in fig. 1.<br />

No s<strong>of</strong>tmode is evident<br />

over all wave vectors,<br />

indicating that the Pbcm<br />

phase has a dynamically<br />

stable structure. The<br />

ferroelectric behavior <strong>of</strong><br />

AgNbO3 thus cannot be<br />

explained based on this.<br />

Extensive calculations are<br />

under way to uncover the<br />

correct ferroelectric<br />

transition mechanism <strong>of</strong><br />

this compound.<br />

References<br />

1. D. Fu, et al., Appl. Phys. Lett. 90, 252907 (2007).<br />

2. L. Levin, et al., Phys. Rev. B 79, 104113 (2009).<br />

3. M. Yashima, et al., Chem. Mater. 23, 1643 (2011).<br />

Figure 1. Phonon dispersion curve for the room temperature<br />

phase (Pbcm) <strong>of</strong> AgNbO3.<br />

Acknowledgements<br />

This work was supported by Green network <strong>of</strong> excellence (GRENE).<br />

P- 90


Author Index


Author Index : Name and Abstract<br />

(A)<br />

Ahmed I. Ali P- 36<br />

Atsushi Ashida P- 25<br />

Chang Won Ahn I- 8, P- 2, P- 3, P- 18,<br />

P- 27, P- 35, P- 37,<br />

P- 61<br />

Gantsooj Amarsanaa P- 88<br />

H. Adachi P- 23<br />

J. S. Ahn P- 43<br />

Jun Akedo I- 20<br />

Md. Noor-A-Alam P- 87<br />

Muhtar Ahart P- 69<br />

Yukikuni Akishige P- 83<br />

(B)<br />

Alexei A. Bokov I- 16, P- 69, P- 72<br />

Insung Bae I- 4<br />

J. S. Bae P- 68<br />

Masahiko Bekki P- 83<br />

Sang Don Bu P- 21<br />

Shuvrajyoti Bhattacharjee P- 31<br />

Sunggi Baik P- 4, P- 44<br />

(C)<br />

Byung Chun Choi P- 81<br />

C.I. Cheon P- 60<br />

C.-W. Cho P- 68<br />

DongHyuk Choi P- 81<br />

EuiyoungChoi P- 75<br />

H. I. Choi P- 14<br />

Hae In Choi P- 15, P- 58, P- 79, P- 80<br />

J. H. Choi P- 60<br />

jin Ho Choi P- 37<br />

Jinsik Choi P- 50<br />

K. W. Chae P- 60<br />

Kang Ho Choi P- 18<br />

M. R. Cha P- 68<br />

Myoung Pyo Chun P- 78<br />

Pice Chen I- 14<br />

Seong Kyu Cheon P- 1<br />

Song A Chae P- 2, P- 3, P- 18<br />

S-W. Cheong PL-1, P- 45, P- 46<br />

Taekjib Choi P- 50<br />

Yong-Jai Cho P- 4<br />

(D)<br />

D. Do P- 14, P- 59<br />

Dalhyun Do P- 15, P- 44, P- 58, P- 79,<br />

P- 80<br />

Eric M. Dufresne I- 14<br />

Feng Dang C- 3<br />

Matthew Dawber I- 14<br />

Thi Hinh Dinh P- 27<br />

Tran Minh Dao P- 76<br />

(E)<br />

Paul G. Evans I- 14<br />

Seongmun Eom P- 67<br />

(F)<br />

Craig A. J. Fisher P- 90<br />

Desheng Fu P- 90<br />

Eiji Fujii I- 12<br />

H. Funakubo P- 22<br />

Hironori Fujisawa P- 38, P- 39, P- 48,<br />

P- 49<br />

Hiroshi Funakubo I- 7, P- 12<br />

Ichiro Fujii P- 63, P- 74, P- 77<br />

John G. Fisher C- 5<br />

M. Fukada P- 23<br />

M. Fukunaga P- 47, P- 55<br />

N. Fujimura P- 26<br />

Norifumi Fujimura P- 25<br />

S. Fujiyama P- 47<br />

S. Furukawa P- 45<br />

Yuto Fujita P- 34<br />

(G)<br />

E. A. Goremychkin P- 45<br />

T. Guidi P- 45<br />

(H)<br />

A. Hussain C- 7, P- 28, P- 59, P- 66<br />

Ali Hussain P- 57<br />

C. Hyon P- 55<br />

Chang Jo Han P- 20<br />

Changhyo Hong P- 73<br />

Cheol Seong Hwang C- 4, P- 7, P- 13<br />

Dae-Jun Heo P- 27, P- 73<br />

H. Hiraka P- 47<br />

Hajime Haneda C- 3<br />

Hyoung-Su Han I- 8, P- 27, P- 57, P- 73<br />

Jin Kyu Han P- 21<br />

Motoaki Hara I- 10<br />

Myunghoon Han P- 85<br />

Sahwan Hong P- 50<br />

Seung Ho Han P- 37<br />

Suck Won Hong I- 3<br />

Sung Kyoung Hong P- 78


Sung-Ok Hwang P- 40<br />

Sungwon Ha P- 81<br />

Taejun Hwang P- 76<br />

Tsukasa Hirayama I- 18<br />

Won Joon Heo P- 85<br />

Y. Horibe C- 1, P- 46<br />

Yoichi Horibe P- 71<br />

Yoon-Hwae Hwang I- 3<br />

Yuki Hidaka P- 72<br />

(I)<br />

Hikaru Igawa P- 52<br />

Hiroaki Imai C- 3<br />

Jun Ikeda P- 33<br />

Junnya Ikeda P- 83<br />

Kei Iwamoto P- 52<br />

Makoto Iwata P- 30<br />

Masafumi Iwaki I- 10<br />

Masashi Igawa P- 39<br />

Mitsuru Itoh I- 15<br />

Mutsuo Ishikawa I- 7<br />

N. Ikeda C- 1<br />

Noriyuki Inoue P- 32<br />

Shotaro Ishikawa P- 8<br />

Takahiro Ishii P- 54<br />

Y. Iqbal P- 66<br />

Yoshihiro Ishibashi P- 30<br />

Yoshihisa Ishikawa P- 56<br />

Yuichi Ikuhara I- 18<br />

(J)<br />

Anquan Jiang P- 7<br />

Byeong-Eog Jun P- 67, P- 81<br />

Byung Chul Jeon I- 6, P- 16<br />

Dae-Yong Jeong P- 62<br />

Dongwon Jang P- 81<br />

Doo Seok Jeong P- 7<br />

Gun Sang Jeon P- 45<br />

Ho-Young Joo P- 50<br />

Hui Jung P- 81<br />

J. Y. Jang P- 68<br />

Jaehong Jeong P- 45<br />

Ji Young Jo I- 14, P- 17, P- 20<br />

Jihoon Jeon P- 50<br />

Jin Suk Jeong P- 16<br />

Jong Hoon Jung P- 6<br />

Jong Shik Jang P- 4<br />

Seong Su Jeong P- 1<br />

W. Jo C- 2, P- 43<br />

(K)<br />

Akihide Kuwabara P- 90<br />

Akihiro Kohori I- 9<br />

Akitoshi Koreeda P- 53<br />

Chang Soo Kim P- 4<br />

Chiaki Kobayashi P- 49<br />

D. J. Kim P- 14, P- 68<br />

Da Jeong Kim P- 15, P- 58, P- 79, P- 80<br />

Dong Jin Kim P- 67<br />

H. J. Kim P- 41, P- 42<br />

H. Kimura P- 47<br />

Hajime Kishi P- 38<br />

Han Joon Kim C- 4, P- 7, P- 13<br />

Ha-Nul Kim C- 5<br />

Hiroyuki Kimura P- 56<br />

Hye-Jung Kim P- 86, P- 87<br />

Hyo Kyeom Kim C- 4, P- 13<br />

Ill Won Kim I- 8, P- 2, P- 3, P- 18, P- 35,<br />

P- 37, P- 61, P- 88<br />

Isao Kagomiya C- 6<br />

Isao Kagomiya P- 9<br />

J. S. Kim C- 7, P- 28, P- 60<br />

J. W. Kim P- 22, P- 41, P- 42<br />

Jae-Hyeon Ko I- 16, P- 35, P- 65<br />

Jin Ho Kwak P- 21<br />

Jin-Kyu Kang P- 73<br />

Jin-Soo Kim P- 50<br />

Jongdae Kim P- 5<br />

Junichi Kaneshiro P- 70<br />

K. Kobayashi P- 46, P- 55, P- 71<br />

K. Komaki P- 23<br />

K. Kurushima P- 46, P- 71<br />

Kazumi Kato C- 3<br />

Ken-ichi Kakimoto C- 6, P- 9<br />

Kensuke Kato C- 6<br />

Kyung Joong Kim P- 4<br />

M. H. Kim C- 7, P- 14, P- 28, P- 41,<br />

P- 42, P- 59, P- 66<br />

Makoto Kuwabara C- 3<br />

Masafumi Kobune P- 38, P- 48, P- 64<br />

Minoru Kurosawa I- 7<br />

Myong Ho Kim P- 1, P- 15, P- 44, P- 58,<br />

P- 79, P- 80<br />

Na Lee Kim P- 1<br />

Nobuhiro Kumada P- 63, P- 74, P- 77<br />

R. Kumai P- 55<br />

Richard Hahnkee Kim I- 4<br />

Ryo Kishimoto P- 38<br />

S. S. Kim P- 41, P- 42<br />

S. W. Kim P- 14<br />

S.-A. Kim P- 47<br />

Sadaharu Kato P- 30<br />

Sang Su Kim P- 15, P- 58, P- 79, P- 80


Sang Wook Kim P- 15, P- 58, P- 79,<br />

P- 80<br />

Satoshi Kimura P- 38<br />

Seiji Kojima I- 16, P- 34, P- 35, P- 52,<br />

P- 54, P- 65, P- 69, P- 72<br />

Seok Ju Kang I- 4<br />

Sergei V. Kalinin P- 50<br />

Shin-Ae Kim P- 45<br />

T. Kanashima P- 11<br />

Tae Heon Kim I- 6, P- 10, P- 16,<br />

Tae Hyun Kim I- 16, P- 34, P- 35, P- 65<br />

Takashi Kamiyama P- 84<br />

Takeyuki Kikuchi P- 38<br />

V. Kiryukhin P- 45<br />

W. J. Kim C- 7, P- 14, P- 28, P- 41,<br />

P- 42, P- 59, P- 66,<br />

Won Jeong Kim P- 15, P- 44, P- 58,<br />

P- 79, P- 80<br />

Won-June Kim P- 85<br />

Y. J. Kim P- 41, P- 42<br />

Y. Kawahara P- 26<br />

Yong Baek Kim P- 45<br />

Yong Soo Kim P- 36<br />

Yong Su Kim P- 16<br />

Yoshihiro Kuroiwa P- 8, P- 31, P- 32,<br />

P-33, P- 74, P- 77,<br />

P- 84<br />

Yoshihisa Kato I- 12<br />

Yu Jin Kim C- 4, P- 7, P- 13<br />

Yukihiro Kaneko I- 12<br />

Yunseok Kim P- 50<br />

Yuuki Kitanaka P- 8, P- 84<br />

(L)<br />

C. Lefevre C- 2<br />

C.-H. Lee P- 47<br />

Dae-Gi Lee C- 5<br />

Daesu Lee I- 6, P- 16<br />

Eok Kyun Lee P- 85<br />

Hee Young Lee P- 40<br />

Ho Nyung Lee I- 14<br />

Hosang Lee P- 50<br />

Ho-Yong Lee C- 5<br />

Hyeon Jun Lee P- 17<br />

Hyun-Young Lee P- 57<br />

J. Lin P- 47<br />

Jae-Shin Lee I- 8, P- 27, P- 57, P- 73<br />

Jaichan Lee I- 13, P- 75, P- 76, P- 89<br />

Jai-Yeoul Lee P- 40<br />

Jeong Keun Lee P- 62<br />

Jeong-Pyo Lee P- 4<br />

Jong-Pil Lee P- 62<br />

Jung Hoon Lim P- 1<br />

M. H. Lee P- 14<br />

Myang Hwan Lee P- 15, P- 16, P- 44,<br />

P- 58, P- 79, P- 80<br />

S. H. Lee P- 68<br />

S.Y.Lim P- 59<br />

Seongsu Lee P- 45<br />

Soo Whan Lee P- 62<br />

Sun-Young Lee P- 37<br />

Suyeol Lee P- 67<br />

Woo Lee P- 4<br />

Xifa Long I- 16<br />

Yunsang Lee P- 75<br />

Yun-Soo Lim P- 62<br />

(M)<br />

Abdel Moez P- 36<br />

Akifumi Morishita P- 84<br />

C. Meny C- 2<br />

Chikako Moriyoshi P- 8, P- 31, P- 32,<br />

P- 33, P- 74, P- 77,<br />

P- 84<br />

Eisuke Magome P- 33, P- 77<br />

Hiroki Moriwake I- 15, P- 31, P- 90<br />

Ken-ichi Mimura C- 3<br />

Masaki Maeda P- 30<br />

Masaru Miyayama P- 8, P- 84<br />

Michio Miura I- 10<br />

Partha S. Mondal P- 76<br />

Rizwan Ahmed Malik P- 57<br />

Ryuta Mitsui P- 63<br />

S. Mori C- 1, P- 46<br />

Seung Eon Moon P- 5<br />

Shigeki Miyasaka P- 56<br />

Shigeo Mori P- 71<br />

Takashi Matsuda I- 10<br />

Tatsuya Mori P- 52<br />

(N)<br />

Dieu Nguyen C- 5<br />

Hiroshi Nishioka P- 38, P- 64<br />

K. Nakajima P- 45<br />

K. Nishida P- 22<br />

Kouichi Nakashima P- 63, P- 74, P- 77<br />

S. Nakashima P- 11<br />

Seiji Nakashima P- 38,P- 39, P- 48,<br />

P- 49<br />

Serge M. Nakhmanson I- 14<br />

Sin-Hye Na I- 11<br />

T. Nagata C- 1<br />

T. Nakao P- 23


Tae Won Noh I- 6, P- 12, P- 16<br />

Takahiro Nakano P- 56<br />

Tea Won Noh P- 10<br />

Tokihiro Nishihara I- 10<br />

Van Quyet Nguyen P- 27, P- 57<br />

Y. Noda P- 47, P- 55<br />

Yu Nishitani I- 12<br />

Yuji Noguchi P- 8, P- 84<br />

Yukio Noda P- 56<br />

(O)<br />

Haruka Okuda P- 64<br />

J. -J. Oak P- 41, P- 42<br />

Jeong-Hyeon Oh C- 5<br />

M. Okuyama P- 11<br />

Mayuko Ogawa P- 32<br />

Minoru Osada I- 2<br />

P. V. Ong P- 89<br />

S. H. Oh C- 2<br />

Takafumi Okamoto P- 32<br />

Takeshi Oguchi P- 8<br />

(P)<br />

Baeho Park P- 50<br />

Bong Chan Park P- 61<br />

Cheolmin Park I- 4<br />

Dhananjai Pandey P- 31<br />

Dong-Soo Park P- 62<br />

Hyunjun Park P- 67<br />

J. S. Park P- 14<br />

Je-Geun Park P- 45<br />

Jin Su Park P- 15, P- 58, P- 79, P- 80<br />

Jong Kyu Park P- 1<br />

Jung Min Park P- 11<br />

Min Hyuk Park C- 4, P- 7, P- 13<br />

S. Park P- 68<br />

Sang-Joon Park P- 4<br />

Se-Jeong Park I- 3<br />

Tae Gone Park P- 1<br />

Youn Jung Park I- 4<br />

(R)<br />

C. M. Raghavan P- 41, P- 42<br />

G. H. Ryu C- 7, P- 28, P- 59<br />

Hyun Rhu P- 4<br />

Jungho Ryu P- 40, P- 62<br />

(S)<br />

H. Shima P- 22<br />

Hae Jin Seog P- 2, P- 37<br />

Hiroyuki Sakurai I- 9<br />

Hyun-A Song I- 11<br />

James F. Scott P- 12<br />

Ji Won Seo I- 13<br />

Jong Yeog Son P- 51<br />

Kengo Shibata P- 82<br />

Kohei Suzuki P- 34<br />

Kouhei Suzuki P- 69<br />

M. Sohgawa P- 11<br />

Masaru Shimizu P- 38, P- 39, P- 48,<br />

P- 49<br />

Muneyasu Suzuki I- 20<br />

R. H. Shin C- 2, P- 43<br />

Rebecca J. Sichel I- 14<br />

Rikiya Sano I- 17<br />

Shota Seto P- 48<br />

Sung Min Seo P- 19<br />

T. K. Song C- 7, P- 14, P- 28, P- 41,<br />

P- 42, P- 59, P- 66<br />

Tae Kwan Song P- 15, P- 16, P- 44,<br />

P- 58, P- 79, P- 80<br />

Takahisa Shiraishi I- 7<br />

Takayoshi Sasaki I- 2<br />

Takeshi Sakashita I- 10<br />

Tatsuya Shimoda I- 5<br />

Terutoshi Sakakura P- 56<br />

Tomohiko Shibata P- 54<br />

Y.-S. Seo P- 43<br />

Yeon Soo Sung P- 44<br />

Yeong Jae Shin P- 10<br />

Yoshio Satoh I- 10<br />

Young Jae Shin I- 6, P- 12<br />

Young-Han Shin P- 51, P- 85, P- 86,<br />

P- 87<br />

Yukio Sato I- 18<br />

(T)<br />

Haruki Takayama P- 54, P- 69<br />

Hiroki Taniguchi I- 15<br />

Hiroyuki Tanaka I- 12<br />

Kazuaki Taji P- 31<br />

Kazuki Tanaka P- 30<br />

Kenji Tsuda I- 17<br />

Kohei Tsuchida P- 9<br />

Masaki Takesada P- 53<br />

Michiyoshi Tanaka I- 17<br />

Naoki Toyota P- 52<br />

Shinji Taniguchi I- 10<br />

Shinya Tsukada P- 72, P- 83<br />

Shoichi Takeda P- 33<br />

Shuki Torii P- 84<br />

Y. Togawa P- 46<br />

Yoshinori Tokura P- 56<br />

Yuhji Tsujimi P- 29<br />

Yusuke Takada P- 48


(U)<br />

Aman Ullah P- 61<br />

Amir Ullah P- 61<br />

Hokuto Usami P- 70<br />

K. Ujimoto P- 26<br />

Masanori Ueda I- 10<br />

Michihito Ueda I- 12<br />

Yoshiaki Uesu PL-2<br />

(V)<br />

N. Viart C- 2<br />

(W)<br />

K. Wakazono P- 26<br />

M. Watanabe P- 55<br />

Satoshi Wada C- 3, P- 63, P- 74, P- 77<br />

Sung Sik Won P- 2, P- 3<br />

T. Wada P- 23<br />

Takahiro Wada I- 9, P- 24, P- 82<br />

Won Seok Woo P- 2, P- 3<br />

Yeong Sung Wang P- 5<br />

Zhong Lin Wang P- 6<br />

(Y)<br />

A. Yamashita P- 55<br />

Byung Kil Yun P- 6<br />

Byung Youn You P- 4<br />

Chang-Ho Yoon P- 57<br />

Chan-Ho Yang I- 1<br />

Dong Jin Yoon P- 40<br />

Hiroko Yokota P- 70<br />

Hironori Yoshimura P- 77<br />

Hyunsuk Yoon P- 67<br />

Hyunung Yu P- 4<br />

Il-Hyuk Yoo C- 4<br />

Il-Hyuk Yu P- 13<br />

Jong Gul Yoon P- 16<br />

Jong-Gul Yoon I- 6, P- 10, P- 12, P- 19<br />

K. Yakushi P- 55<br />

K. Yamamoto P- 55<br />

Ken Yanai P- 84<br />

Kenta Yamashita P- 74, P- 77<br />

S. Yamazoe P- 23<br />

Sang Mo Yang I- 6, P- 10, P- 12, P- 16<br />

Seiji Yamazoe I- 9, P- 24, P- 82<br />

Seongtak Yoon P- 75<br />

Soon-Gil Yoon I- 11<br />

T. Yamamoto P- 22<br />

T. Yoshimura P- 26<br />

Tae-Sik Yoon I- 19<br />

Takeshi Yoshimura P- 25<br />

Tomori Yanagisawa P- 29<br />

Toshirou Yagi P- 53<br />

Tsuyoshi Yokoyama I- 10<br />

Woo Seok Yang P- 5<br />

Yoshiki Yachi P- 25<br />

Yu Yamamoto P- 24<br />

Zuo-Guang Ye I- 16, P- 69, P- 72<br />

(Z)<br />

A. Zaman P- 66

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