ICMCTF 2012! - CD-Lab Application Oriented Coating Development

as-grown films using textured Si as a base substrates and compared the
results with the films grown on polished Si substrate. Thin films of LiCoO2
were prepared by rf magnetron sputtering technique on
Au/Ti/SiO2/(polished)Si and Au/Ti/SiO2/(textured)Si maintained at a
substrate temperature 300 o C. Comprehensive investigation was performed
on the growth, microstructure and electrochemical properties of thick
LiCoO2 films deposited at various reactive gas composition and rf powers.
The as-grown LiCoO2 films on polished Si metalized substrate at low O2 to
Ar gas composition ratio of 1:9 and rf power 150 W exhibited predominant
(0 0 3) orientation representing partially ordered HT-LiCoO2 structure with
R3m crystalline space group. The average surface area fraction observed
from SEM analysis is observed to be 4.1 %. The films exhibited first
ordered phase transition during intercalation/de-intercalation reaction and
demonstrated a discharge capacity of 53 µAhcm -2 µm -1 with a higher
capacity fading rate of 0.26 %. Where as, the films deposited on
Au/Ti/SiO2/(textured)Si substrates represented predominant (0 0 3)
orientation with relatively enhanced surface area fraction of 16.7 %. The
surface of the film observed from SEM contains pyramidal shaped clusters
composed of grains with an average size of 210 nm. These films exhibits
improved electrochemical performance in terms of discharge capacity (57.5
µAhcm -2 µm -1 ), capacity retention (95.4% per 50 cycles) and lower capacity
fade rate (0.07 % per cycle) which is demonstrated by the substrate
texturing influence.
FP-4 The Grain Evaluation and Electrochemical properties of RF
sputtered LiMn2O4 thin films., J. Babu, J. Kumar, O. Mahammad
(hussainsvu@gmail.com), Sri Venkateswara University, Thin Films
Laboratory, India, V. Ramana, University of Texas at El Paso, US
Abstract:
Lithium transition metal oxides have received a considerable attention in
recent years as high voltage positive electrode materials in the fabrication of
all solid state microbatteries. Among various lithium based cathode
materials, LiMn2O4 is one of the most promising cathode material as it
offers high energy density, high cell voltage, low cost, and low toxicity over
the other electrode materials. In the present investigation, thin films of
LiMn2O4 were prepared by radio frequency magnetron sputtering on gold
coated silicon substrates in an Oxygen to Argon ratio of 1:6 and an oxygen
partial pressure of 2×10 -2 mbar. The films were deposited from different
substrate temperatures ranging from 400 K – 700 K and RF power was
varied from 50-125 W. The influence of substrate temperatures and RF
power on growth, microstructure and electrochemical properties was
studied. The XRD and SEM results revealed that with the increase of
substrate temperature the film structure changed from amorphous to
polycrystalline. The films deposited at Ts = 673 K with RF power 80 W
exhibited predominantly (111) orientation representing cubic spinel
structure of Fd3m symmetry with an average grain size and lattice
parameter of 275 nm and 8.23 Å. Further increase in crystallanity and
electrochemical performance was observed by annealing these films at
700 0 C. The films annealed at 973 K exhibited better electrochemical
performance with initial discharge capacity of 53.5 μAh cm -2 μm -1 in the
aqueous media suggesting that the film can be used as binder free cathode
in Li-ion battery application.
FP-5 Electrochemical Properties of V2O5 Thin Films Grown on
Flexible Substrates using Plasma Assisted Activated Reactive
Evaporation, K. Hari Krishna, University of Calabria, Italy, O.M. Hussain
(hussainsvu@gmail.com), Sri Venkateswara University, India
Vanadium Pentoxide (V2O5) thin films have been deposited using home
built plasma assisted activated reactive (ARE) evaporation on ITO coated
flexible Kapton substrates and investigated their microstructural and
electrochemical properties. X-ray diffraction patteren displayed
predominent (001) orientation by designating the Orthorhombic structure of
the films deposited at optimized growth conditions. The surface of the films
is obseerved to be composed of vertical elliptically shaped nanosized grains
of size 98 nm provided with an estimated rms roughness of 9 nm as
evidenced from AFM studies. At room temperature, the as-deposited V2O5
films demonstrated a dischage capacity of 60 μAh(cm 2 - μm) for 10 cycles
in the potential window of 4.0 V - 2.5 V. The influence of silver (Ag) interlayer
on electrochemical properties of V2O5 films is investigated and
observed appreciable increment electrochemical performance of multilayered
'V2O5/Ag/V2O5' films. The multi-layered 'V2O5/Ag/V2O5' films
demonstrated a discharge capacity of 75 μAh(cm 2 - μm) provided with
enhanced cyclicability.
FP-6 Bismuth thin films deposited by DC Magnetron Sputtering for
electrochemical analysis electrodes, S.E. Rodil, P. Silva-Bermudez
(suriel21@yahoo.com), J. Baron, O. Garcia-Zarco, Instituto de
Investigaciones en Materiales, Universidad Nacional Autónoma de Mexico,
México
In the last ten years, Bismuth-film electrodes (BiFEs), prepared by coating a
suitable substrate with a metallic Bi thin film, have proved valuable tools
for electroanalysis in the reductive potential regime, especially for anodic
and adsorptive stripping analysis. They have been proposed as a green
alternative to substitute Hg film electrodes.
In order to evaluate the physicochemical properties and the electrochemical
behavior of Bi films produced by DC magnetron sputtering and to assess
their feasibility to be used as BiFEs for detection of heavy metal traces in
water, in the present work Bi films were deposited by DC magnetron
sputtering onto glass substrates using a high purity Bi target (99.9 at. %, 4”
in diameter), a working pressure of 4 Pa (Ar atmosphere), a current density
of 0.2 A and deposition times of 5, 10 and 15 minutes.
The structural properties of the films were characterized by X-ray
Diffraction, X-ray Photoelectron Spectroscopy and Raman Spectroscopy.
The thickness, roughness and dielectric constant of the films were also
characterized. The structure of the deposited films was basically the Birhombohedral
phase with a preferred orientation (012) & (104). The films
were polycrystalline and have large deposition rates.
For the electrochemical tests of the films, a 1 cm 2 area was exposed to
buffer solutions. First, the potential window of the films at which the
electrode might be useful and their stability upon potentiostatic extreme
conditions were characterized in buffer solutions of pHs 4.6, 7 and 10, in an
electrochemical cell with a saturated calomel reference electrode and a Pt
wire as the counter electrode. No strong variations in the potential windows
with deposition time (film thickness) were observed. The oxidation
potential became more negative as the pH increased, from -0.3 to -0.5 V.
The potential windows were about 1 V for all the films in the 3 different
pHs.
After determination of the potential window an electrochemical impedance
spectroscopy test was performed; the spectra were very similar for the 3 pH
values and the different film thickness, probably indicating similar
interfacial effects. Then, the samples were subjected to a cyclic potential
from -1.5 to 1.5 V; the films could support these extreme conditions without
undergoing delamination. Finally, the performance of the films as BIFEs
was evaluated by anodic adsorptive stripping analysis in water solutions
containing either, Cu or Sn traces.
Acknowledgements to funding from the European Community Seven
Framework Programme (FP7-NMP-2010-EU-MEXICO) and CONACyT
under grant agreements nº 263878 and 125141; and to the ICyTDF
postdoctoral fellowship for P. S-B
FP-7 SnO2-cored heteronanowires sheathed with metal shells and their
application to gas sensors, H.W. Kim (hyounwoo@hanyang.ac.kr),
Hanyang University, Republic of Korea
The current trend towards downsized integrated electronic and optical
devices has strongly motivated the intensive study of various onedimensional
(1D) nanostructures. In particular, one attempt has been made
to create coaxial 1D structures with a core/sheath geometry, which may
assist in the realization of various tailor-made functions by assembling the
different features of both nanowires (as cores) and nanotubes (as sheaths)
with different chemical compositions in the radial direction. Indeed, the
great potential has recently been demonstrated in nanodevice applications
such as coaxial-gated transistors and laser diodes. SnO2 is a well-studied
functional material that has been extensively used in dye-based solar cells,
transparent conducting electrodes, and gas sensors.
Pre-grown SnO2 1D nanostructures are coated via a DC sputtering
technique using a metal target. By carrying out the subsequent thermal
annealing, we have generated the metal nanoparticles on the core
nanowires. M etallic catalysts are known to functionalize the surface of
nanomaterials. For example, n oble metals anchored on semiconducting
oxides facilitate the dissociation of oxygen molecules into oxygen species,
including atomic oxygen, thereby enhancing the oxygen sensitivity.
Accordingly, some research groups have attempted to functionalize the
surface of oxide nanowires with nanosized noble metals using various
methods. In the present work, we have investigated the effect of metal
nanoparticles on the gas sensor properties of nanowires. .
FP-8 Enhancement of electron-emission and long-term stability in tiptype
carbon nanotube field emitters by lithium coating, J.S. Park,
B.J. Kim, J.P. Kim, J.S. Park (jinsp@hanyang.ac.kr), Hanyang University,
Republic of Korea
Recently, carbon nanotubes (CNTs) have been researched to develop a high
resolution x-ray image system for medical applications such as early
117 Thursday Afternoon Poster Sessions