bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of ZnO Coating on the Electrochemical Performance of LiMn1.5Ni0.5O4 Cathode Material
Authors: Singhal Rahul , Tomar Maharaj S , Burgos Juan G , Kumar Arun , Katiyar Ram S 
Published: April 2011

AbstractLiMn1.5Ni0.5O4 cathode material was prepared by sol-gel method and annealed at 850°C for 15 hrs. The prepared powder was coated with ZnO by dissolving zinc acetate in methanol and LiMn1.5Ni0.5O4 powder was mixed in this solution followed by the continuous stirring for 4 hr. The LiMn1.5Ni0.5O4 and ZnO coated LiMn1.5Ni0.5O4 powder was characterized using X-ray diffraction, TEM and Raman spectroscopy. The coin cell was fabricated using LiMn1.5Ni0.5O4 and ZnO coated LiMn1.5Ni0.5O4 as cathode materials, LiPF6, dissolved in EC/DMC (1:1 wt ratio) as electrolyte, and Li foil as anode. The cyclic voltammetric and charge-discharge characteristics were carried out for the coin cell using LiMn1.5Ni0.5O4 and ZnO coated LiMn1.5Ni0.5O4 cathode materials. It was found that the ZnO coated LiMn1.5Ni0.5O4 cathode materials showed improved discharge capacity (∼146mAh/g) as compared to the pure LiMn1.5Ni0.5O4 (∼140mAh/g). The discharge capacity retention after 50 cycles was found to be about 94% and 97% for LiMn1.5Ni0.5O4 and ZnO coated LiMn1.5Ni0.5O4 cathode materials, respectively.
Influence of Lithium Content on Performance of Layered Li1+z[Ni0.45Mn0.45Co0.1]1-zO2 in Lithium Ion Batteries
Authors: Xiao Jie , Chernova Natasha A. , Whittingham M. Stanley 
Published: April 2011

AbstractLi1+z[Ni0.45Mn0.45Co0.1]1-zO2(0.8≤1+z≤1.2) has been synthesized by the co-precipitation method. It was found that 5% excess lithium must be added to obtain the desired composition. XRD results show that an apparent single-phase structure appears except for the lowest lithium content. The layered character of the structure increases with increasing lithium content and Rietveld refinement reveals that cation disorder decreases rapidly as more lithium is added. This conclusion is further confirmed by magnetic studies in which only Li0.8[Ni0.45Mn0.45Co0.1]1.2O2 and Li0.9(Ni0.45Mn0.45Co0.1)1.1O2 show magnetization hysteresis loops. The electrochemical behavior of this series of samples is compared to figure out the best lithium to transition metal ratio.
Electrochromic Nickel Hydroxide Thin Films Chemically Deposited
Authors: Araceli Monica , Vidales-Hurtado  , Mendoza Arturo 
Published: April 2011

AbstractNickel hydroxide thin films were deposited on ITO-coated glass substrates by the chemical bath deposition method. Two formulations using nickel nitrate were employed to obtain the films. The first one is through coordination compounds by using an ammonia complex producing the well crystallized phase β(II)-Ni(OH)2. The second formulation is based on the decomposition of urea at temperatures above of 90 °C, which promotes the deposition of the turbostratic phase α(II)- Ni(OH)2. After thermal annealing in air at temperatures of 250-300 °C, the β(II) films retain their polycrystalline structure, while the α(II) films are partially transformed to NiO. The electrochromic behavior of the films was tested by cyclic voltammetry in a three electrodes configuration cell. Also, chronoamperometry and in-situ single wavelength transmittance measurements were carried out to evaluate the switching time response. From Raman spectroscopy the structural transformations between colored and blanched states were studied. In the colored state most of the films show a mixture of β(III) and γ(III) phases of NiOOH, and in one case the Ni2O3 phase was found. It is shown that the films can exhibit high optical contrast depending on the processing conditions and electrical potential applied.
Effect of Water on the IR Properties of Mg2+ Intercalated Electrochromic Nb2O5 Thin Films
Authors: Agarwal Gargi , Reddy G B 
Published: April 2011

AbstractSol-gel derived Nb2O5 thin films were intercalated with Mg2+,using the non-aqueous solution of Mg(ClO4)2 in propylene carbonate (pc) as the electrolyte. 2% and 4% ( volume %) water was added to the electrolyte to study the effect of water on the electrochromic properties of Nb2O5. This paper presents the changes in optical and structural properties of the intercalated films with and without water in the electrolyte. The ratio (x) of the Mg2+ and Nb atoms has been controlled by optimizing the intercalation duration under a constant current density. The fall in transmittance on intercalation (for x= 0.8) increased by 15% with 4% water in the electrolyte, compared to the film intercalated without water. FTIR studies show that water is incorporated in the films on intercalation and small quantities of Mg(OH)2 and Nb-OH are formed along with Mg-O-Nb bonds. The presence of water in electrolyte decreases water content in the films and enhances the formation of Mg(OH)2, Mg-O-Nb and Nb-OH bonds. The recovery of Mg2+ on deintercalation is slightly reduced in presence of water in the electrolyte. The cyclic stability of the films intercalated without water is more than that of the films intercalated in presence of water.
High Performance Single Step Co-Fired Solid Oxide Fuel Cells
Authors: Yoon Kyung Joong , Gopalan Srikanth , Pal Uday B. 
Published: April 2011

AbstractAnode-supported planar solid oxide fuel cell (SOFC) was successfully fabricated by a single step co-firing process. The cell comprised of a Ni + yittria-stabilized zirconia (YSZ) anode, a YSZ electrolyte, a Ca-doped LaMnO3 (LCM) + YSZ cathode active layer, and an LCM cathode current collector layer. The fabrication process involved tape casting of the anode, screen printing of the electrolyte and the cathode, and single step co-firing of the green-state cells at 1300°C for 2 hours. The maximum power densities were 1.50W/cm2 at 800°C, and 0.87W/cm2 at 700°C with humidified hydrogen (97% H2-3% H2O) as fuel and air as oxidant. The experimentally measured I-V curves were fitted into a polarization model to obtain cell parameters including the area specific ohmic resistance, exchange current density, effective binary diffusivity of hydrogen and water vapor in the anode, and that of oxygen and nitrogen in the cathode. The cell was also tested at 800°C with various compositions of humidified hydrogen to evaluate the cell performance at high fuel utilization, and the maximum power densities were 1.30W/cm2 with 75.7% H2-24.3% H2O, 0.94W/cm2 with 49.4% H2-50.6% H2O, and 0.49W/cm2 with 27.3% H2-70.7% H2O.
Scandia – Stabilized Zirconia: Effect of Dopants on Surface/Grain Boundary Segregation and Transport Properties
Authors: Smirnova A. , Sadykov V. , Muzykantov V. , Mezentseva N. , Ivanov V. , Zaikovskii V. , Ishchenko A. , Sammes N. , Vasylyev O. , Kilner J. , Irvine J. , Vereschak V. , Kosacki I. , Uvarov N. , Zyryanov V. 
Published: April 2011

AbstractThe nanocrystalline samples of 10wt.%Scandia stabilized Zirconia (10ScSZ) and 1wt.%Ceria doped ScSZ (1Ce10ScSZ) prepared via co-precipitation route were characterized and compared to commercially available samples regarding their transport properties and electrical conductivity. The results of oxygen isotope experiments show that for Zirconia-based electrolytes, the rate of heteroexchange is lower than that for Samaria-doped Ceria. The results of Secondary Ions Mass Spectrometry (SIMS) indicate that all admixed components are present both in the surface layer and the bulk of the studied samples with pronounced segregation on the grain boundary. The highest total conductivity is observed for DKKK sample. In the range of 600-400°C the highest conductivity observed for synthesized nanocrystalline 1Ce10ScSZ sample is explained by the effect of segregated Scandia doped Ceria surface layers.
Safety Characteristics of the Li4Ti5O12/LiMn2O4 Li-Ion Battery
Authors: Belharouak Ilias , Lu Wenquan , Amine Khalil 
Published: April 2011

AbstractLi4+xTi4O12 and Li1-yMn2O4 materials have been respectively prepared by a chemical lithiation of Li4Ti4O12 in the presence of an excess of butylithium (LiC4H9) in hexane solution and chemical delithiation of LiMn2O4 spinel using NO2BF4 oxidizer in an acetonitrile medium. The thermal gravimetric results show that Li1-yMn2O4 releases oxygen starting from 200°C with an overall oxygen loss of 6 wt% at 500 °C, whereas Li4+xTi4O12 gains oxygen starting from 200 °C with an overall oxygen gain of 4 wt % at 500 °C. The reactivity of the Li4+xTi4O12 and Li1-yMn2O4 powders in the presence of electrolytes was investigated by a differential scanning calorimetry (DSC) between room temperature and 375°C, and compared to a lithiated graphite in the case of the Li4+xTi4O12 negative electrode material.
Influences of Microstructures of the Cathode/Electrolyte Interface on the Electrochemical Properties of All Solid-State Li-ion Batteries
Authors: Kishida Kyosuke , Wada Naoyuki , Yamaguchi Yuji , Tanaka Katsushi , Iriyama Yasutoshi , Ogumi Zempachi , Inui Haruyuki 
Published: April 2011

AbstractTwo types of samples containing different La2/3-xLi3xTiO3 (LLT) solid electrolyte /LiCoO2 cathode interfaces were prepared by depositing LiCoO2 on polycrystalline LLT with two different surface finishes: cleaved and polished surfaces. Electrochemical properties of the samples were analyzed by cyclic voltammetry (CV). Microstructures of the LLT/LiCoO2 interfaces were investigated by scanning electron microscopy and transmission electron microscopy. Cyclic voltammograms of the cleaved sample show that the anodic and cathodic peaks respectively shift to higher and lower potential with the number of cycles, while those for the polished samples do not change much during cycles of potential sweeps, indicating the higher stability for the polished samples upon insertion and extraction of lithium ion. The LiCoO2 thin-film cathode is epitaxially deposited with the orientation relationships: {110}LLT//{1120}LiCoO2 and <001>LLT//<4401>LiCoO2 for both samples with different geometric configurations of the interfaces to the Li layers in the LiCoO2. Amorphous regions are observed to exist in places at the interface only in the polished samples. The geometric configuration of the interface and the existence of the amorphous regions are considered to have great influences on the stability of the LLT/LiCoO2 interfaces upon charge / discharge operations.
Microfabricated Solid State Thin Film Lithium Batteries
Authors: Salot Raphael , Salot Raphael , Pereira-Ramos Jean-Pierre 
Published: April 2011

ABSTRACTThis work presents recent advances in the development and the integration of a solid state thin film battery, to work as a high voltage energy source for RF-MEMS powering. Micro-electro-mechanical systems require similarly miniaturized power sources. Up to day, microbatteries are realized with mechanical masks, this method doesn't allow dimensions below several decades of mm2 of active area, and besides the whole process flow is done under controlled atmosphere so as to ensure materials chemical stability (mainly lithiated materials). Within this context, Microelectronics micro-fabrication procedures (photolithography, Reactive Ion Etching…) are used to reach both miniaturisation (100×100 μm2 targeted unit cell active area) and microelectronic IC technological compatibility. The whole process is realized in clean room environment. The thin film battery is composed of three active layers. First the positive electrode layer of crystalline vanadium pentoxide c-V2O5, the next level presents then the solid state electrolyte, a glassy ionic conducting material commonly known as “LiPON”. Finally, a negative electrode top level is realized by the evaporation of metallic lithium. The total stack thickness is of about 10 μm. A final wafer level packaging step is then realized to avoid reactivity with air and moisture. Specific attention will be put on the microfabrication processes developed for the positive electrode and the electrolyte (etching chemistry, resist stripping…). Several electrochemical characterizations (spectroscopic electrochemical impedance, charge-discharge cycling) were performed before and after micro-fabrication process steps so as to evaluate any possible effect on the electrochemical behaviour of the different studied layers.
Temperature Dependence Study of Gas Permeability in Metal Doped Composite Polymeric Membranes
Authors: Vijay Yogesh Kumar , Jain Anil Kumar , Acharya Naveen Kumar , Awasthi Kamlendra , Kulshrestha Vaibhav 
Published: April 2011

ABSTRACTPolycarbonate (PC) membrane and PC based hydrogen active intermetallic compound Fe0.5Ti0.5 particles doped composite membrane have been prepared by solution cast method. The membranes have been characterized by H2 and CO2 permeability and selectivity measurements with increasing temperature. Higher gas permeation has been observed with increasing temperature. In case of doped composite membrane H2/CO2 gas pair selectivity first increases then decreases with temperature whereas in case of pure PC it decreases with temperature. The effect of doping increases the activation energies for permeation of H2 and CO2 in the doped membrane in comparison to pure PC. Doping was found to suppress plasticization effect in polycarbonate. The doped membrane was analyzed by optical micrograph and XRF study.
Mechanical-to-Electrical Energy Conversion of Thin-Film Piezoelectric Diaphragms
Authors: Morris Dylan J , Robinson Michelle C , Weiss Leland W , Richards Cecilia D , Richards Robert F , Bahr David F 
Published: April 2011

ABSTRACTA micro (∼1 cm3) dynamic heat engine, capable of producing electrical power from lowgrade heat sources, utilizes a micro-machined diaphragm with a piezoelectric element as a The electromechanical coupling of a piezoelectric diaphragm under large initial stresses and/or large deflections – in the membrane limit – is described here. A simple model is derived for electromechanical transduction of a pressurized piezoelectric membrane and an experiment is described to measure it. Electromechanical coupling initially increases as the square of the center-point deflection as the residual stress is overcome. In the limit of large pressures, the electromechanical coupling approaches a limit that is predicted by the model.
Evaluation of Polycrystalline Silicon for Solar Cells by Small p-n Diode Array
Authors: Tanaka Satoshi , Imai Keita , Ogura Atsushi , Ohshita Yoshio , Arafune Koji , Kawai Hideaki , Kusuoka Futoshi , Tajima Michio , Inoue Masaaki 
Published: April 2011

ABSTRACTA small p-n diode array was fabricated on a polycrystalline Si substrate and the electrical characteristics were measured for each small diode to evaluate the distribution of energy conversion efficiency in the substrate. The crystal qualities in conjunction with the electrical characteristics were also evaluated. We found large variations in measuring the current-voltage (I-V) characteristics of the p-n diode. We also observed variations in quality even in diodes without any grain boundaries at the p-n junction. Therefore, we evaluated crystalline quality using various techniques to compare the diode characteristics. We found clear evidence in photo-luminescence (PL) mapping, where grains, including degraded diodes, were darker in the mapping, implying lower PL intensities than the others. The PL spectra obtained from the “dark grains” included D-lines indicating the existence of dislocations. We could conclude that the electrical characteristics of p-n diodes were not only affected by grain boundaries but also by crystalline defects evaluation such as dislocations. We observed a Secco-etched surface for crystalline defects evaluation using an optical microscope. The origins of etch pits were also determined by transmission electron microscope (TEM) and three different types of defects were confirmed.
Silicide Mediated Grown Silicon Thin Films for Photodiodes
Authors: Kim Joondong , Anderson Wayne A. , Han Chang-Soo , Lee Eung-Sug 
Published: April 2011

ABSTRACTQuality Si thin films were grown by the metal-induced growth (MIG) method. Metal (Co, Ni, or mixing of Co and Ni) was thermally evaporated on a 200 nm-SiO2 coated Si wafer. Si sputtering was performed at 600 – 620 °C in a dc magnetron system. The reaction of Si and metal first formed a silicide (CoSi2 or NiSi2) layer and further Si sputtering grew a Si film above it. The grown Si films were practically fabricated for Schottky photodiodes and electrically measured under one sun scan illumination (100 mW/cm2).
Characteristics of Chemically Deposited Thin Film Solar Cells using SnS and Sb2S3 Absorbers
Authors: Nair M. T. Santhamma , Avellaneda David , Messina Sarah , Nair P. K. 
Published: April 2011

ABSTRACTWe use SnS and Sb2S3 thin films of about 500 nm in thickness deposited on glass substrates by chemical deposition to develop solar cell structures: glass-SnO2:F/CdS/SnS/CuS/silver paint and SnO2:F/CdS/Sb2(S/Se)3/PbS/silver paint. Here, SnS and Sb2S3, and PbS are absorber materials suitable for large scale production, considering their abundance at 0.2 ppm (Sb) and 2 ppm (Sn) and 8ppm (pb) in the earth's crust according to published data. SnS films deposited through distinct reaction routes have optical band gap of 1.1 eV or 1.7 eV. In SnO2:F/CdS/SnS(1.1eV)/SnS(1.7 eV)/CuS/silver paint, open circuit voltage (Voc) of ≈ 400 mV, and short circuit current (Jsc)of 7 mA/cm2 are obtained with a cell efficiency of 1%. Sb2S3 thin films have optical band gap 1.7 eV, but could be reduced through reaction in Se-vapor, upon which solid solutions of Sb2(S/Se)3 are formed. In SnO2:F/CdS/Sb2(S/Se)3/PbS/silver paint, Voc of ≈ 640 mV, Jsc of 7 mA/cm2 and conversion efficiency of 1.5% are obtained.
Comparison of Common Segmentation Techniques Applied to Transmission Electron Microscopy Images
Authors: Sadowski Thomas , Broadbridge Christine C. , Daponte John 
Published: April 2011

ABSTRACTNanoparticles are of interest in many applications since their decreased size may give them properties that are very different from bulk material. Often nanoparticle properties such as size (diameter) and size distribution are evaluated using transmission electron microscopy (TEM). These parameters, size and size distribution, can be more easily obtained from digitized TEM images by mapping particle signal to black and background pixel to white in a process known as thresholding then performing an algorithm known as a particle analysis. The goal of this study was to compare the ability of several popular thresholding algorithms to segment TEM images. Performance of the thresholding algorithms was evaluated through qualitative and quantitative measures. Results show that the choice of a thresholding algorithm will strongly affect the results obtained from particle analysis.
Determination of Inelastic Mean Free Path by Electron Energy-Loss Spectroscopy in TEM: A Model Study Using Si and Ge
Authors: Wang Chongmin , Cannon Bret D. 
Published: April 2011

ABSTRACTAlthough the inelastic mean free path for Si and Ge have been measured previously, reported experimental values for silicon range from 121 nm to 160 nm for 200 keV and a large collection angle. A key factor responsible for this uncertainty is the lack of an accurate measurement of the specimen thickness at the point at which the EELS spectra are obtained. In this research, we have evaluated a systematic methodology for determination of the specimen thickness. In the thickness measurement based on converging beam electron diffraction, CBED, instead of the classic “trial and error” straight-line-fitting method to either the maxima or minima, a non-linear least square fitting of the theoretical diffraction profile to the energy filtered two-beam CBED is used. The low-loss EELS spectrum is also obtained from the same location. The inelastic mean free path was determined using the measured thickness and EELS data. Furthermore, attempt is also made to obtain the dielectric function from the low-loss spectrum. The established method will be extended to other materials and the results will be compared with numerical simulations.
Enhancing Light-trapping and Efficiency of Solar Cells with Photonic Crystals
Authors: Biswas Rana , Zhou Dayu 
Published: April 2011

AbstractA major route to improving solar cell efficiencies is by improving light trapping in solar absorber layers. Traditional light trapping schemes involve a textured metallic back reflector that also introduces losses at optical wavelengths. Here we develop alternative light trapping schemes with a-Si:H thin film solar cells, that do not use metallic components, thereby avoiding losses. We utilize low loss one-dimensional photonic crystals as distributed Bragg reflectors (DBR) at the backside of the solar cells. The DBR is constructed with alternating layers of crystalline Si and SiO2. Between the DBR and the absorber layer, there is a layer of 2D photonic crystal composed of amorphous silicon and SiO2. The 2D photonic crystal layer will diffract light at oblique angles, so that total internal reflection is formed inside the absorber layer. We have achieved enhanced light-trapping in both crystalline and amorphous silicon solar cells at near-infrared wavelengths where absorption lengths are very large. Very high absorption is achieved throughout optical wavelengths. The optical modeling is performed with a rigorous 3 dimensional scattering matrix approach where Maxwell¡¯s equations are solved in Fourier space.
Dielectric Properties of Ultra Dense (3 g/cm3) Silicon Nitride Deposited by Hot Wire CVD at Industrially Relevant High Deposition Rates
Authors: Houweling Zomer Silvester , Verlaan Vasco , van der Werf Karine , Goldbach Hanno D. , Schropp Ruud E I 
Published: April 2011

AbstractFor silicon nitride (SiNx) deposited at 3 nm/s using hot wire chemical vapor deposition (HWCVD), the mass-density reached an ultra high value of 3.0 g/cm3. Etch rates in a 16BHF solution show that the lowest etch rate occurs for films with a N/Si ratio of 1.2, the ratio where also the maximum in mass density occurs. The thus found etch rate of 7 nm/min is much better than that for PECVD layers, even when made at a much lower deposition rate. The root-mean-square (rms) roughness measured on 300 nm thick SiN1.2 layers is only about 1 nm, which is advantageous for obtaining high field-effect mobility in thin-film transistors. SiN1.2 films have succesfully been tested in “all hot wire” thin film transistors (TFTs). SiNx films with various x values in the range 1.0 < × <1.5 have been incorporated in metal-insulator-semiconductor structures with n-type c-Si wafers to determine their electrical properties from C-V and I-V measurements. We analyzed the behavior of the static dielectric constant, fixed nitride charges and trapped nitride charges as function of N/Si ratio. I-V measurements show that the HW SiNx films with N/Si ≥ 1.33 have high dielectric breakdown fields that exceed 5.9 MV/cm. For these films we deduce a low positive fixed nitride charge density of 6.2-7.8 × 1016 cm-3 from the flat band voltage and from the small hysteresis in the backward sweep we deduce a low fast trapped charge density of 1.3-1.7 × 1011 cm-2. The dielectric constant ε for different compositions is seen not to change appreciably over the whole range and amounts to 6.3 ± 0.1. These high-density SiNx films possess very low tensile stress (down to 16 MPa), which will be helpful in for instance, plastic electronics applications. HWCVD provides high quality a-SiNx materials with good dielectric properties at a high deposition rate.