bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Benefits of Process Parameter Ramping During The Plasma Etching of High Aspect Ratio Silicon Structures
Authors: Hopkins J. , Ashraf H. , Bhardwaj J. K. , Hynes A. M. , Johnston I. , Shepherd J. N. 
Published: April 2011

AbstractIn the ongoing enhancement of MEMS applications, the STS Advanced Silicon Etch, (ASETM). process satisfies the demanding requirements of the industry. Typically, highly anisotropic. high aspect ratios profiles with fine CD (critical dimension) control are required. Selectivities to photoresist of 150:1 with Si etch rates of up to 10μm/min are demonstrated. Applications range from shallow etched optical devices to through wafer membrane etches. This paper details some of the fundamental trends of the ASETM process and goes on to discuss how the process has been enhanced to meet product specifications. Parameter ramping is a powerful technique used to achieve the often-conflicting requirements of high etch rate with good profile/CD control. The results are presented in this paper.
Negative Thermal Expansion Behaviour in The NZP Phase NbTi(PO4)3
Authors: Woodcock D. A. , Lightfoot P. , Smith R. I. 
Published: April 2011

AbstractWe present new detailed structural data versus temperature on the Nasicon structured material NbTi(PO4)3 obtained from powder neutron diffraction studies. This material shows a significant volume contraction over the range 20°C < T < 700°C. αa varies between –4.34 and -0.11 × 10-6°C-1 and αc between 0.08 and 3.07 × 10-6°C-1 over this range. This behaviour contrasts with the case of NaTi2(PO4)3 (NaTP) which shows a positive volume expansion. The difference in this behaviour can be explained by the presence of filled MI sites in NaTP which are vacant in the case of NbTP.
New Organometallic and Coordination Chemistry Routes Towards Unsupported and Silica-Supported Bismuth-Based Oxide-Type Materials
Authors: Devillers M. , Lebrun S. , Tirions O. , Wullens H. 
Published: April 2011

AbstractCoordination and organometallic compounds containing bismuth, lanthanum or molybdenum are used as precursors for the preparation of unsupported or silica-supported Bi-based oxides. Bismuth (III) and lanthanum (III) polyaminocarboxylates, and more specifically homo- and heteropolymetallic complexes of triethylenetetraaminehexaacetic acid (H6ttha) are shown to constitute adequate precursors for the formation of mixed Bi2-xLaxO3 oxides at moderate temperatures. Silica-supported bismuth molybdates are obtained from impregnation or combined impregnation-deposition procedures involving Bi ß-diketonates, carboxylates or mixed acetate-Nmethylimidazole Bi complexes, in association with molybdenyl acetylacetonate or heteroleptic carbonyl-pyridine Mo complexes, either dissolved or dispersed in various organic solvents.
Reactivity of SnO2, Ruthenium-Supported SnO2, Ruthenium (Platinum) Ion-Exchanged SnO2 with Inert, Combustible Gases and Air: An Electron Paramagnetic Resonance Study
Authors: Canevali C. , Chiodini N. , Morazzoni F. , Scotti R. 
Published: April 2011

AbstractSnO2, Ru/SnO2 and Pt/SnO2 were prepared by sol-gel condensation method. Ru/SnO2 was also obtained by supporting the metal on SnO2 xerogel. The reactivity of these materials towards CO and air, studied by Electron Paramagnetic Resonance spectroscopy (EPR), suggests that the electron transfer processes at the oxide surface are favored by the presence of the metal, in the order Pt > Ru ion-exchanged > Ru-supported. A rationale was given for the differences and for the choice of a material suitable to high sensitivity gas sensors.
The Valence Electronic Structure of Co3O4: Is It a Charge-Transfer Insulator?
Authors: Langell M.A. , Carson G.A. , Smith S. , Peng L. , Nassir M.H. 
Published: April 2011

AbstractDespite the relevance to a variety of materials applications, the electronic and bonding properties of spinel transition metal oxides are not well established. We report here the slow oxidation of CoO(100) to Co3O4, studied by photoemission (UPS and XPS), low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS) with the aim of elucidating the valence band electronic structure of the Co3O4 spinel. The original Mott insulator picture of the parent CoO substrate has been revised in recent times, after careful analyses and extensive debate, to the more detailed charge-transfer insulator model which includes some admixture of oxygen 2p levels in the 3d-derived valence band. No equivalent band structure analysis has been performed on the spinel oxides, perhaps in part because of the greater complexity of the 56-atom unit cell with two different cation lattice sites and oxidation states. In this study, we determine the valence band structure of the spinel oxide and address the question of whether Co3O4 can be modeled as a charge-transfer insulator in analogy with its closely related rocksalt substrate.
Electronic Properties of Bi and In Substituted Layered Ba4Pb3O10 Compounds
Authors: Kasal R. , Ulanday J. B. , Obien J. , Jayaram B. 
Published: April 2011

AbstractElectronic properties of the layered compounds with the general composition Ban+1(Pb,Bi)nO3n+1 are quite interesting as the crystal structure of these materials is quite similar to that of high-Tc cuprates. We have investigated the effect of Bi and In substitution on the structure, oxygen stoichiometry (carrier concentration) and the electronic properties of Ba4Pb3O10 compounds. The X-ray powder diffraction results indicate that the unit cell symmetry changes from body-centered tetragonal to cubic with the increasing concentration (x) of Bi and In. The oxygen stoichiometry of the materials is found to increase monotonically with the increase in x(Bi). On the other hand it decreased almost linearly with the increasing x(In). Resistivity of the materials is measured as a function of temperature in the temperature region 3-300K. It is found that the room temeprature resistivity increases with increasing x(Bi/In). Since the oxygen stoichiometry values suggest an increase in the carrier concentration with increasing x(Bi/In), it appears that the disorder caused by the substitution at the Pb site has lead to the carrier localization. For x(Bi)<0.2, we found that the resistivity varies as a function of lnT, which is indicative of weak localization. However, at higher concentrations 3D-VRH behavior is observed. On the other hand the resistivity of indium substituted samples show M-I transition, at low concentrations.
Liquid Crystal Behavior of V2O5·nH2O Gels
Authors: Livage J. , Davidson P. , Commeinhes X. , Pelletier O. 
Published: April 2011

AbstractMost liquid crystals are made of organic molecules, very few of them are based on mineral compounds. Vanadium pentoxide gels and sols have been shown to give mesophases. They are made of ribbon-like polymeric particles of vanadium pentoxide dispersed in water. Ansitropic xerogel layers are formed when these gels are deposited and dried onto flat substrates. Dehydration is reversible and fluid phases are again obtained via a swelling process when water is added to the xerogel.When observed by polarized light microscopy, colloidal suspensions of V2O5 ribbons display defects typical of lyotropic nematic phases. Dilute nematic suspensions can even be oriented by applying a magnetic field of about 0.5 Tesla. Such a liquid crystal behavior is mainly due to the highly anisotropic shape of vanadium oxide colloidal particles. Acid dissociation at the oxide/water interface gives rise to surface electrical charges and electrostatic repulsions should also be responsible for the stabilization of the nematic phase.
Phase Formation, Stability and Superconducting Properties of Mechanically Alloyed Yttrium-Nickel-Borocarbides
Authors: Ledig L. , Hough D. , Oertel C.-G. , Eckert J. , Skrotzki W. 
Published: April 2011

AbstractThe solid state reaction of YNi2B2C by mechanical alloying of elemental powders has been investigated by X-ray diffraction, transmission electron microscopy and susceptibility measurements. Depending on the ball milling parameters either nanocrystalline YNi2B2C or an amorphous phase can be produced. Crystallization of the amorphous phase by annealing at 893 K produces YNi2B2C as major and Ni2B as minor intermetallic compound. Superconductivity is only observed in the annealed state. However, the transition temperature is much lower than in arc-melted samples. This is discussed with respect to the nanocrystalline and amorphous state as well as deviations from stoichiometry produced by impurities introduced during milling.
6Li and 7Li MAS NMR and In Situ X-ray Diffraction Studies of Lithium Manganate Cathode Materials
Authors: Lee Young Joo , Wang Francis , Grey Clare P. , Mukerjee Sanjeev , McBreen James 
Published: April 2011

ABSTRACT6Li MAS NMR spectra of lithium manganese oxides with differing manganese oxidation states (LiMn2O4, Li4Mn5O12, Li2Mn4O9, and Li2Mn2O4) are presented. Improved understanding of the lithium NMR spectra of these model compounds is used to interpret the local structure of the LixMn2O4 cathode materials following electrochemical Li+ deintercalation to various charging levels. In situ x-ray diffraction patterns of the same material during charging are also reported for comparison. Evidence for two-phase behavior for x < 0.4 (LixMn2O4) is seen by both NMR and diffraction.
Carbon Powders Prepared in Rf Thermal Plasma and Their Application to Anode of Lithium Secondary Baltery
Authors: Kurihara M. , Uchida S. , Maruyama S. , Takizawa T. , Moriyoshi Y , Ishigaki T , Sato Y 
Published: April 2011

ABSTRACTCarbon powders prepared by the RF thermal plasma treatment of phenolic resin were examined for the anode materials of lithium secondary battery. Modification of these carbon powders in chemical composition, crystal structure and surface morphology was characteristics of the thermal plasma treatment The treated powders showed the unique microstructure. TEM observation showed the non-uniform distribution of graphitized and amorphous areas in the particles. The electrochemical measurements as an anode for lithium secondary battery were examined in IM LiClO4in a 50:50 mixture of ethylene carbonate and diethyl carbonate. While the electrochemical extraction of lithium ion from plasma-prepared carbon powders proceeded in three stages, the electrochemical insertion looked to proceed in two stages. These electrochemical features can be associated with the uncommon microstructure characteristics.
Thin Films of Ionic Conductors by Laser Ablation
Authors: Morcrette M. , Barboux P. , Perrière J. , Laurent A. , Boilot J. P. , Brousse T. 
Published: April 2011

ABSTRACTFilms of insertion compounds and solid state electrolytes have been synthesized in order to study their applications in the domain of electrochemical ion and gas sensors. Laser ablation was used to deposit lithium metal oxides (LiMO2 where M is a transition metal Co or Mn).The chemical composition in the films has been studied by Rutherford Backscattering spectrometry and nuclear reactions analysis in the case of the light elements (O, Li). For lithium transition metal oxides (LiMO2), the oxygen and lithium contents are determined by a thermodynamical equilibrium between the films and the partial pressures in the chamber. In these cases, laser ablation allows the synthesis of crystalline structures with a large range of oxygen non stoichiometry as compared to solid state reactions. They lead to interesting electrical properties. Using the appropriate temperatures and oxygen pressures, films with the correct stoichiometry could be obtained as polycrystalline onto Si or Si/Pt substrates whereas they exhibit high texturing and epitaxial growth onto MgO or MgO/Pt.The films of LiMn2O4 and LiCoO2 have been used as electrochemical sensors for the measurement of the lithium concentration in solutions. They show a very rapid and selective response.
Understanding of Lithium Insertion into λ-MnO2 Compounds
Authors: Sarciaux S. , Salle A. Le Gal La , Verbaere A. , Piffard Y , Guyomard D. 
Published: April 2011

ABSTRACTA large variety of EMD and HTMD samples with various oxygen and water contents and various structural parameters Pr and Mt has been prepared. We show that the physico-chemical and structural parameters of the λ-MnO2 compounds are related to the synthesis conditions. New compounds were obtained with unusual amounts of intergrowth and twinning defects.The Li insertion study focuses on a comprehensive investigation of the relationships between the material characteristics of the samples and their Li insertion behavior, and on the structural characterization of selected compounds after cycling. The oxygen content drastically affects the shape of the discharge curve after the first cycle and the total reversible capacity. The amount of structural water has an influence on the transformation kinetics of the starting phase. For optimized oxygen content (y= 2 in MnOY), the intrinsic reversible Li insertion capacity is maximum when the amount of microtwinning defects is minimum and when the structure is either mostly Ramsdellite or faulted Pyrolusite. Results show that, upon cycling, the λ-MnO2 structure seems to evoluate towards less Pyrolusite defects together with the apparition of new kinds of defects.This work shows that λ-MnO2, compounds could be good candidates for the cathode application of Li-metal rechargeable batteries, provided that the physico-chemical and structural parameters of the starting compound are well chosen.
Knowledge Discovery in Conducting Polymeric Composite Devices: AN Essential Research Towards New Computer/Sensing Information Devices
Authors: Talaie A. , Eisazadeh H. , Adachi K. , Taguchi T. , Romagnoli J.A. , Buniran S. 
Published: April 2011

ABSTRACTA composite of two conducting polymers, polyaniline and polypyrrole, could result in much improved physical properties with respect to their applications in pH electrodes and conducting paints/coatings. However, the composite has time dependant properties that made the use of dynamic computational algorithms necessary to control its behaviour. We used a sandwich-modified electrode as a pH-sensing electrode, which was integrated with a pre-trained computer for data processing and knowledge discovery. Conducting polypyrrole/polyaniline colloidal composites have been also prepared by deposition of the mixture solution of polypyrrole and polyaniline at negative potentials. Different substrates were dipped in the solution containing the mixture together with an acrylic latex and after drying the adhesive strength and electroactivity of the paint were studied. Several colloidal composite based coatings were investigated. At last a computer facilitated with powerful artificial ncural network based algorithms classified the paints.
Ionic Space Charge Relaxation and High Dielectric Permittivity in Polyethylene Oxide
Authors: Wagner A. , Kliem H. 
Published: April 2011

ABSTRACTThin films (0.3μm to 11.2 μm) of Polyethylene Oxide (PEO) with molecular weights from 6 × 103 to 4 × 105 were prepared from aqueous solutions by a spin technique as AI-PEO-AI structures, or as AI-PEO-Si structures. Dielectric measurements (capacitance and loss angle) were carried out in a frequency range 3 mHz ≤ f ≤ 1 MHz in atmospheres of different relative humidity (0% r.h. to 75% r.h.) and at different temperatures (293 K to 323 K). The nominal dielectric permittivity exhibits a remarkable dependence on the sample thickness and the relative humidity. We find a true volume polarization in the high frequency range and a thermally activated relaxation process in the low frequency range, whose time constant is shifted towards high frequencies with increasing r.h.. It is considered that due to the absorbed dipolar water molecules chemical bonds within the sample are broken and quasi-free ions are generated. These ions move through the sample to the electrode interfaces and form an ionic space charge. We assume that at the PEO-Al interface an oxide layer is formed, which is impermeable for these ions. The transit times and the drift velocities of the ions are almost independent of the electric field strength in the low-field limit. Therefore we conclude that the movement of the ions can be described by a multiwell potential model, where the transition probability between neighbored wells is thermally activated.
An Improved Composite Polymer Electrolyte for Lithium Metal Batteries
Authors: Mastragostino M. , Soavi F. , Zanelli A. 
Published: April 2011

ABSTRACTWe have demonstrated that PEO-based polymer electrolytes prepared by solvent-free procedures and with the addition of particle-size ceramic powder have very stable lithium interface properties—a very important feature for the development of successful lithium metal polymer batteries (LPBs). The results of cyclability tests at different charge-discharge rates carried out on prototypes of LPBs assembled with the dry prepared PEO20-LiCF3SO3-20%w/w λLiAlO2 composite electrolyte and with a composite cathode based on LiMn204 spinel operating at 3V are reported and discussed.
Synthesis of Ceramics/Polymer Nanocomposites Protonic Conducting Membrane
Authors: Honma I. , Hirakawa S. , Bae J.M. 
Published: April 2011

ABSTRACTHigh temperature protonic conducting polymer membrane provides new technological applications in the electrochemical devices including electrochromic displays, chemical sensors, fuel cells and others. Organic/inorganiaianocomposites membrane consists of SiO2/PEO (Polyethylene Oxides) hybrid are remarkable family of isotropic, amorphous polymer materials, which has been synthesized through sol-gel processes. The hybrid membrane doped with acidic surfactant molecules shows good protonic conductivities at high temperatures above 100C. The membrane was found to be thermally stable at high temperatures because of the inorganic SiO2 framework in the composites matrix.
Mixed Alkali Effect as a Retarding Effect of Secondary Diffusion Processes in Glass
Authors: Belostotsky Vladimir 
Published: April 2011

ABSTRACTIon mobility in mixed alkali glass is discussed in the context of the recent experimental observation that oxygen diffusion from molten salt into glass accompanies the replacement of smaller alkali ions for larger alkali ions during ion exchange. The assumption is made that simultaneous migration of two unlike monovalent cations induces, among other things, oxygenexchange diffusion between sites. Diffusing oxygen molecules form additional fluctuating sites or traps lying along the ion pathways between regular ionic sites. Instead of jumping directly to the regular ionic site, mobile ions are forced to execute several additional hops between fluctuating sites, and this results in significant reduction in ion mobility.
The Role of Effective Rate Constants in Interfacial Kinetics
Authors: Maier Joachim 
Published: April 2011

ABSTRACTA brief excerpt of a more comprehensive quantitative theoretical analysis on the role of effective rate constants in interfacial processes is given (in particular [1], see also [2,3]). Chemical incorporation, tracer incorporation and steady state electrical experiments are considered. It is shown that besides experimental differences there are mechanistic and conceptual differences between the three effective rate constants (kδ, k*, Qq). The treatment based on irreversible thermodynamics and chemical kinetics shows similarities and differences with respect to the analogous situation in the bulk. As special cases adsorption and transfer limited kinetics are considered. Having related the k-values to the exchange rates of the rate determining step and to the chemical capacitance outside the boundary zone, the characteristic dependencies on controlling parameters and also the correlation with diffusion coefficients can be derived. This is done for electron-rich materials such as SOFC cathodes. A further point which is briefly mentioned in this context is the fact that flux constriction effects may lead to apparent surface rate constants. The role of space charges is briefly discussed for the case of grain boundary kinetics [4]. In electron-poor materials such as SrTiO3(Fe2O3) or Zr02(Y203) additional mechanistic differences should occur, since in the tracer case mechanisms are possible at the surfaces which do not have to involve electrons directly. Here also discrepancies with respect to electrical experiments are predicted (leading to a surface analogue of a Haven ratio). Some experimental results obtained with SrTiO3 are discussed in this context.
Determination of Diffusion Coefficient of Impurity Ions in a Crystal from their Drift Under Electric Field
Authors: Akopyan A.A. , Kislyuk V.V. , Pekar G.S. 
Published: April 2011

ABSTRACTWe studied the drift of Cd interstitials in CdS single crystals at an electric field applied to the crystal. These atoms are totally ionized at moderate temperatures of the investigation (300 - 400 K). Mobile Cd ions drift from the anode to the cathode. A time-dependence was studied experimentally for the voltage dropped on the crystal at the constant value of the current passed through the sample. A non-stationary problem developed for the transient process allowed to derive the ion mobility in such a process from the experimental data. Concentration profiles and their time history were investigated in detail for the ions and free carriers.
Doping of Ionic Compounds: Solubility Limit and Charge Compensation
Authors: Tsur Y. , Riess I. 
Published: April 2011

ABSTRACTAn analysis is presented that allows calculating properties of primary solid solutions in ionic crystals. These properties are expressed in terms of properties of the undoped host material and the impurity.One can calculate the solubilities of the impurities with a knowledge of the concentration of what is defined as the “corresponding native species”, the standard chemical potential of the materials involved and the local shear modulus of the host material.The changes in concentrations of ionic point defects as well as electron/hole concentrations due to doping are also calculated. In order to do so one has to know the concentrations of the native point defects in the undoped host material and the concentration of the dopant. It is shown that in a native p-type semiconductor (e.g., Cu20) extrinsic donors are mainly self-compensated by ionic defects, while extrinsic acceptors are compensated significantly by holes.
Electrical Conductivity in Nanocrystalline ZrO2:Y
Authors: Kosacki Igor , Petrovsky Vladimir , Anderson Harlan U. 
Published: April 2011

ABSTRACTThe electrical conductivity of nanocrystalline thin films and bulk microcrystalline ZrO2:16%Y (YSZ) has been studied as a function of oxygen activity and correlated with the microstructure. Nonacrystalline films are characterized by enhanced conductivity and different stoichiometry compared with microcrystalline specimens. The interpretation of the results is based on a defect pair association model with partly ionizated acceptor and donor centers.
The Synthesis and Electrical Conductivity of Novel Mixed Ionic and Electronic Conductors in The Gd2GaSbO7-Gd2Zr2O7 Solid Solution
Authors: Takamura H. , Tuller H. L. 
Published: April 2011

ABSTRACTThe synthesis and electrical conductivity of a novel solid solution pyrochlore Gd2GaSbO7 - Gd2Zr2O7 were studied as a function of x in Gd2(GaSb)1-xZr2xO7 (0 ≤ x ≤ 1). In this study, single phases with the pyrochlore structure were obtained in the range of x ≤ 0.2, while a garnet phase appeared as a minor second phase for x ≥ 0.3. In the x = 0.2 sample, evidence of the displacement of 48f oxygens towards the normally empty 8b site was suggested by Rietveld analysis. The total electrical conductivity of the pyrochlores was 2.6x 10−2 S/m for x = 0.0 and 6.0×10−3S/m for x = 0.2 at 1273 K, respectively. In addition, evidence for n-type semiconductivity was obtained for x = 0.2 under reducing conditions. Further studies are underway to identify the dominant carriers under oxidizing conditions.