Photonic crystals in biology

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+ P = Poster Session, Tuesday, June 15 Theme A1 - B702 1 Coated Multi-Walled Carbon Nanotubes with Ceria Nanoparticles 1 Evgeniya Koval’s’kaP PO.O. Chuiko Institute of Surface Chemistry, Nat. Acad. f Sci. of Ukraine; 17, Gen. Naumov Str., Kyiv 03164, Ukraine Abstract-The composites have been received by sedimentation of oxides on surface multi-wall carbon nanotubes (MWNTs). The nanocomposites of were identified by transmission electronic microscope. The crystalline structure was verified by electron diffraction pattern and X-ray spectroscopy. Also XPS spectra were performed on the MWNT samples. The combination of carbon nanotubes (CNTs) with other nanocrystals is expected to be useful for applications in catalysts, sensors, nanoelectronic devices, polymer or ceramic reinforcement. In the paper [1], the authors highlight opportunities for decorating CNTs with a broad range of functional metal oxides including CeR2ROR3R and/or CeOR2R, AlR2ROR3R, LaR2ROR3R, in SC COR2R modified with ethanol. For example, the nanocomposites of CNTs and cerium are very interesting for further studies on their physical and chemical properties. In this paper, the composites have been received by sedimentation of oxides on surface multi-wall carbon nanotubes (MWNTs) from solutions by a reaction: 4Ce(NOR3R) R3R 12NaOH + OR2R 4CeOR2R + 12NaNOR3 R+ 6HR2RO . A certificated catalytic MWNTs (Nanothinx S. A.) having 12–31 nm diameters, 15–35 walls and 97 % purity (about 2 % is iron catalyst and less 1 % is pyrolytic carbon) was used. The nanocomposites of CeRxRORyR/MWNTs were identified by transmission electronic microscope (TEM), and their crystalline structure was verified by the selected area electron diffraction (SAED) pattern and X-ray spectroscopy. Figure 1 shows the MWNTs. TEM images of modified MWNTs show the ceria nanoparticles on the MWNTs surface. The size of the particles is 6-10 nm. SAED indicates the rings pattern of nanoparticles can be indexed using the facecentered cubic polycrystalline structure of cerium oxides. MWNT bundles were functionalized with hydroxyl and carbonyl. The deposition of ceria particles on the MWNT bundles depended on the surface state of the MWNT bundles. We believe that the methodology described here expands the Intensity (a.u.) Intensity (a. u.) 20000 15000 10000 5000 Ce3d O1s 1000 800 600 400 200 0 Binding energy (eV) C1s MWNTs a Ce x O y (5.2%)/MWNTs Ce x O y (31%)/MWNTs Intensity (a.u.) 8000 6000 4000 2000 C-O C-C C=O O-C=O 0 280 284 288 292 296 300 Binding energy (eV) 12000 C-C c 8000 C-C d 9000 6000 6000 4000 3000 C-O C=O O-C=O 2000 C-O 0 280 284 288 292 296 300 0 280 284 288 292 296 300 Binding energy (eV) Binding energy (eV) Intensity (a.u.) C=O O-C=O s (c). (d). Figure 2. Total XPS spectra of the purified MWNTs, CeRxRORyR(5.2%)/MWNTs and CeRxRORyR(31%)/MWNTs (a). XPS spectrum of carbon (C1s) in the purified MWNTs (b). XPS spectrum of carbon (C1s) in the CeRxRORyR(5.2%)/MWNTs (c). XPS spectrum of carbon (C1s) in the CeRxRORyR(31%)/MWNTs b functionality chemistry of CNTs and opens up a new avenue for coating one-dimensional nanostructures with various metal oxides and construction of designed nanoarchitectures. Figure 1. TEM images of MWNTs (a), modified MWNTs by ceria (5.2 %, b) and modified MWNTs by ceria (31 %, c). To further investigate the surface state of the MWNTs and the mechanism of ceria coating on the MWNTs, XPS spectra were performed on the MWNT samples. Figure 2 shows the XPS spectra of the purified MWNTs and the ceria-coated CeRxRORyR(5.2%)/MWNTs and CeRxRORyR(31%)/MWNTs, respecttively. The atomic ratio of Ce/O/C in the sample CeRxRORyR(5.2%)/MWNTs calculated from the XPS spectrum is about 1.1 : 1 : 18 and in the sample CeRxRORyR(31%)/MWNTs is about 1.1 : 1 : 3.6 which indicates that there are still large amount of functional groups on the surface of the MWNTs after the deposit process. Ceria nanoparticles with diameter of about 6–10 nm were successfully deposited on the MWNT bundles by a chemical reaction of Ce(NOR3R)R3R with NaOH solution. The synthesis was done in the aqueous solution at room temperature that reduces cost of the preparation procedure of nanosized ceria. The *Corresponding author: evgeniya1209@ukr.net [1] Z. Sun, X. Zhang, B. Han, Y. Wu, G. An, Z. Liu, S. Miao, Z. Miao, Carbon 45, 2589 (2007). 6th Nanoscience and Nanotechnology Conference, zmir, 2010 411
Poster Session, Tuesday, June 15 Theme A1 - B702 Cerium-doped yttrium iron ga rnet thin films with nano s ize regions prepared by s ol-gel process Yavuz Öztürk* 1 , Mustafa Erol 2 ,Erdal Celik 2 1 1 Ege University Electrical and E lectronics Department, 35100 Bornova, Izmir-TURKEY. 2 Dokuz Eylul -TURKEY. Abstract- Cerium doped yttrium iron garnet (Ce x Y 3-x Fe 5 O 12 ; Ce-YIG) magneto-optical thin films were fabricated on Si (100) substrates by using sol-gel method for magneto-optical applications. Ce doped YIG films with nano size regions fabricated with dip coating from solutions prepared from Ce, Y and Fe-based precursors, solvent and chelating agent at low temperature using a sol-gel technique. Coated thin films annealed at the temperature range of 800 and 1000 o C for 2 h in air. Morphological, structural and magnetic properties were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). New technological applications such as magnetic sensor, optical wave-guides, magneto-optical modulator and integrated magneto-optic devices are required improved sensitivity, smaller size and compatibility with electronic systems. Ce substituted yttrium iron garnet (Ce x Y 3-x Fe 5 O 12 ; Ce-YIG) have appeal for these kind of applications due to their magnetic and magneto-optic properties [1,2]. Sol-gel processing offers considerable advantages such as better mixing of the starting materials and excellent chemical homogeneity in the final product [3]. The available Ce-YIG material research has mainly on a single crystals and thin films [4,5]. Polycrystalline Ce-YIG, produced by using solgel method, has rarely been investigated. In this study, we have presented garnet films synthesized by using sol-gel method. Ce, Y and Fe based precursor materials dissolved in methanol and glacial acetic acid (GAA) were used as a solvent for the synthesis of materials. Si(100) were used as substrates. Different solutions prepared with different GAA ratios and constant molarities. The pH values of 3.5 ml Ce:YIG gel solutions with 1.5 ml, 1ml, and 0.5 GAA were 3.6, 3.05 and 2.5, respectively. Higher GAA concentration leads to poor wetting and lower one leads to unsolved precursors. So we used solution with 1 ml GAA. Ce-YIG gel films were dip-coated on the substrates at room temperature. This process was followed by heat treatment by annealing films between 800-1000 °C for 2 hours in air. (a) c) d) Figure 2. SEM and AFM result of Ce:YIG prepared at 1000 °C The magnetization curve of Ce-YIG phase observed with VSM at room temperature. As can be seen from Fig. 3 measured saturation magnetization value of Ce-YIG is lower than bulk YIG (136 emu/cc) [5]. Magnetization (emu/cc) 60 40 20 0 -20 CEYIG1000EH (b) -40 Intensity (a.u) CEYIG1000EH CEYIG900EH CEYIG800EH 20 30 40 2 50 60 : Y 3 Fe 5 O 12 (Kübik) : Unknown Figure 1. XRD patterns of Ce-YIG films coated on Si(100) annealed at 800 °C, 900 and 1000 °C for 2 h. Figure 1 shows XRD patterns of selected samples. All produced samples contains cubic YIG phase. However, there is unknown phase which is reducing at higher annealing temperatures. It is interesting to note that other intermediate phases FeYO3 or/and Fe2O3 were not observed. Fig.2 shows the SEM and AFM results of Ce:YIG annealed at 1000°C. Darker regions have less Si content compared to the lighter regions according to the EDS results. So there is interaction between substrate and garnet phase which leads to nucleation. Roughness of darker regions measured with AFM and as can be seen from Figure 3 nearly smooth surface obtained. -60 -1500 -1000 -500 0 500 1000 1500 Applied Field (Oe) Figure 3. VSM result of Ce:YIG prepared at 1000 °C As conclusion, cerium-doped Y3Fe5O12 garnet films were prepared on Si(100) by sol-gel method using alkoxides of respective elements. Ce:YIG thin films were obtained with cubic YIG phase and good the surface quality. By considering measured hysteresis loop, desired magnetization values were obtained. We believe that sol-gel technique with alkoxide route is the promising method to prepare thin garnet films. This work has been supported by The Scientific and Technological Research Council of Turkey (TUBITAK). *Corresponding author: yavuz.ozturk@ege.edu.tr [1] T. Shintaku, T. Uno, Jpn. J. Appl. Phys. 35 (1996) 4689–4691 [2] A. Tate, T. Uno, S. Mino, A. Shibukawa, T. Shintaku, Jpn. J. Appl. Phys. 35 (1996) 3419–3425 [3] L.L Hench, J.K. West, Principles of Electronic Ceramics. John Wiley & Sons, New York (1990) [4] N. Inoue, K. Yamasawa: Elect. Eng. In Jpn. 117 (1996) 1 [5] X. Zhou, W. Cheng, F. Lin, X. Ma, W. Shi, Applied Surface Science 253 (2006) 2108–2112 [6] B. Lax, K.J. Buton, Microwave Ferrites and Ferrimagnetics, McGraw-Hill, NY, (1962) 6th Nanoscience and Nanotechnology Conference, zmir, 2010 412
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