bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solid-State Heteronuclear-Correlation NMR Studies of Multicomponent Phosphate Glasses
Authors: Prabakar S. , Egan J.M. , Wenslow R.M. , Mueller K.T. 
Published: April 2011

AbstractThe correlation between 23Na and 31P nuclei in alkali phosphates has been investigated by cross-polarization MAS NMR spectroscopy. Connectivity between sodium ions with various phosphorus tetrahedra has been demonstrated in a variety of crystalline-and amorphous alkali phosphates. CPMAS NMR experiments were also performed on sodium aluminophosphate glasses from both quadrupolar nuclei (23Na and 27Al) to the phosphorus nuclei to establish connectivity of sodium and phosphorus as well as aluminum and phosphorus nuclei in these systems.
Variable Dimensionality in The Uranium Fluoride / 2-Methyl-Piperazine System: Syntheses and Structures of UFO-5, 6, and 7; Zero, One, and Two Dimensional Materials with Unprecedented Topologies
Authors: Halasyamani P.S. , Francis R.J. , Bee J.S. , O'Hare D. 
Published: April 2011

AbstractThe hydrothermal syntheses and structures of a new series of organically templated UIV materials are presented. The materials, UFO-5 (C5NH14)2(H3O)U2F13, UFO-6 (C5N2H14)2U2F12H2O and UFO-7 (C5N2H14)(H3O)U2F11, exhibit unprecedented topologies as well as represent 0-D (UFO-5), 1-D (UFO-6), and 2-D (UFO-7) phases. By systematic experimentation and utilizing a composition prism, wherein the reagents including H20 are graphically depicted. we have determined stability regions in which UFO-5, 6, and 7 can be synthesized as phase pure products. In addition, through pH measurements we observe a direct relationship between the acidity of the reaction and the dimensionality of the product. We suggest that the increased acidity facilitates condensation of the molecular uranium units in UFO-5. to produce the 1-D UFO-6 and at higher acidity the 2-D UFO-7.
Commensurate and Incommensurate Oxide Structures Related to 2H Perovskite
Authors: Battle P. D. , Blake G.R. , Burley J.C. , Cussen E. J. , Sloan J. , Vente J. F. , Darriet J. , Weill F. 
Published: April 2011

AbstractThe magnetic structures of Ca3LiRuO6 and Ca3NaRuO6 have been deduced from powder neutron diffraction data. In each case successive Ru5+ cations in the [001] chains of the Sr4PtO6-like structure are antiferromagnetically coupled, and nearest-neighbour Ru5+ cations in adjacent chains are also antiferromagnetically coupled.
Rational Synthesis of The Metastable Compounds BixCo4-xFexSb12
Authors: Williams Joshua R. , Hass Joanna , Sellinschegg Heike , Johnson David C. 
Published: April 2011

AbstractThe synthesis of many targeted ternary compounds using conventional synthesis approaches has been unsuccessful because the ternary compounds are thermodynamically unstable with respect to disproportionation to a mixture of binary compounds. Typically these compounds have been synthetic targets based on predictions of enhanced properties. The ternary skutterudites with formula M'xM4Sbl2 (where M' = La, Lu, Y) are prime examples. Compounds with this structure have been found to be very promising thermoelectric materials having both good electrical properties and low thermal conductivities. Inserting heavy M' atoms into this crystal structure has been predicted to further decrease the thermal conductivity by increased phonon scattering. Attempts to make the title compound using conventional synthesis approaches failed due the formation of binary compounds as reaction products. Using modulated elemental reactants we were able to prepare the title compound at 160°C. Annealing at temperatures above 500°C resulted in exothermic decomposition into binary compounds. The Bi containing compounds are therefore thermodynamically unstable with respect to disproportionation at all temperatures. The amount of Bi can be varied by varying the composition of the starting modulated elemental reactant. Preliminary measurements to determine the variation of electrical conductivity and Seebeck coefficient as a function of bismuth content are presented.
New Hydrides of Zr-Based Intermetallic Compounds
Authors: Zavaliy I. Y. 
Published: April 2011

AbstractThe promising hydrogenation properties of oxygen-stabilised qr-phases with filled-Ti2Ni structure type in Zr-M-O systems (M - V, Cr, Mn, Fe, Co, Ni) are shown in this work. Hydrogenation capacity of the representative examples of compounds with 1:1 and 2:1 metal/metal ratio – Zr3V3O and Zr4Fe2Ox – are presented on the dependence of oxygen content in order to discuss its influence on the hydrogen storage capacity of Zr-based η-phases. The hydrogen disproportionation of η-Zr4Fe2Ox as well as oxygenless pseudobinary (Zr0.6Hf0.4)2Fe compounds with the same structure was studied. The reducing of metal matrix stability with the decrease of oxygen content is shown and explained by the increase of the total energy of crystal lattice.
Iron (III) Oxide within Mesoporous MCM-48 Silica Phases: Synthesis and Characterization
Authors: Köhna R. , Bouffaud G. , Richard O. , van Tendeloo G. , Fröba M. 
Published: April 2011

AbstractUsing multiple cycles of wet impregnation, drying and calcination procedures it was possible to form haematite nanoparticles within the pore system of mesoporous MCM-48 silica phase. A decoration/coating of the inner surface of the silica walls was indicated by a reduction of the BET surface area, the pore radius as well as HRTEM and EDX investigations. Existence of small, slightly disordered iron (III) oxide nanoparticles was proved by X-ray absorption spectroscopic measurements.
Synthesis and Characterization of Nickel and Manganese Vanadium Oxides
Authors: Zhang Fan , Zavalij Peter , Whittingham M. Stanley 
Published: April 2011

ABSTRACTWe have synthesized novel nickel and manganese vanadium oxides using the hydrothermal reactions of vanadium(V) pentoxide, Ni(CH3COO)2, and MnSO4 with an organic templating cation at 165°C. The [NH2(CH2)2NH2]2NiV6O14 has a monoclinic structure. It has some disordered V and 0 atoms in the V6014 layer, which appear to be very close to each other with occupation factor around 0.5. The disordered model was decomposed for two ordered configurations, which differ in the stacking of the layers. The (Mn+2)6(Mn+3)l−2/3z(OH)3(1−Z)(VO4)3[(VO4)l−2z(v207)z] (Z≈0. 1) phase has a hexagonal pipe morphology. These compounds were also characterized by electron microprobe, FTIR and TGA. They reacted readily with lithium, and their electrochemical behavior in lithium cells was determined.
Electron Microscopy Investigation of the Cycling-Induced Phase Transformation in LiMnO2 Compounds
Authors: Wang H. , Jang Y.-I. , Chiang Y.-M. 
Published: April 2011

ABSTRACTLithium transition metal oxides used as intercalation electrodes for rechargeable lithium batteries are widely studied in search of structural stability and improved electrochemical performance. Recent studies showed that the orthorhombic and monoclinic LiMnO2 compounds, unlike LiMn204 spinels, could be cycled on both the 4 V and 2.9 V plateaus with high and stable discharge capacity. In this study, we have performed direct high resolution observations of electrochemically cycled LiMnO2 particles in the fully discharged state. Extensive damage including local strain variation, nanodomain formation, and changes in cation ordering, has been observed. Individual particles retain overall single crystallinity despite having differing structures at the nanodomain level. While cycling causes a macroscopic transformation to spinel cation ordering, the formation of nanodomains differing in cation ordering and/or composition appears to accommodate or prevent the destructive Jahn-Teller distortion that normally occurs at high lithium concentration, thereby resulting in cycling stability.
In situ Synchrotron X-ray Studies on Novel Mn Oxide Spinel Cathodes for Li-ion Batteries: Influence of Other Transition Elements
Authors: Mukerjee S. , Yang X. Q. , Sun X. , Lee S. J. , Mcbreen J. , Ein-Eli Y. 
Published: April 2011

ABSTRACTPartial substitution of Mn in lithium manganese oxide spinel materials by Cu and Ni greatly affects the electrochemistry and the cycle life characteristics of the cathode. Substitution with either metal or a combination of both shortens the 4.2 V plateau associated with the conversion of Mn3+ to Mn4+. A higher voltage plateau associated with oxidation of the substituted transition element is also observed. These substituent also significantly alter the onset of Jahn Teller distortions in the 3 V plateau. Synchrotron based in situ x-ray absorption (XAS) is used to determine the exact nature of the oxidation state changes in order to explain the overall capacities at the different voltage plateaus. Synchrotron based in situ x-ray diffraction (XRD) studies on LiCu0.5Mn1.504 shows single phase behavior in the 4-5 V region and a good cycle life. Lower cycle life characteristics for LiNi0.5Mn1.504 and LiNi0.25Cu0.25Mn1.504 are accounted for on the basis of several phase coexistence in this potential region. In the 3 V plateau however, the LiCu0.5Mn1.504 shows onset of the Jahn Teller distortions, in contrast to the LiNi0.5Mn1.504 and LNi0.25Cu0.25WMn1.504.
Electrochemical Feature of Hydrated Molybdenum Oxides in Lithium Batteries
Authors: Yebka B. , Julien C. , Nazri G.A. 
Published: April 2011

ABSTRACTOxide-hydrates of molybdenum [OHM] are investigated as 3-volt cathode materials for rechargeable lithium batteries. The oxides and oxide-hydrates of molybdenum have been prepared at various degrees of heat treatment. The oxide-hydrates of molybdenum with different water content showed a much better performance as cathode of the rechargeable lithium battery than that of MoO3. From these results, it was found that the crystalline-bonded water molecules play an important role for the high discharge capacity and high cyclability. We report the electrochemical characteristics of Li/OHM batteries using the oxides and oxide-hydrates of molybdenum which have been prepared with various degrees of heat treatment of molybdic acid. The oxide has a corrugated layer structure consisting of corner-shared MoO6octahedra. This structure provide electronic conductivity within a layer and high lithium ion mobility between layers. The mechanism of dehydration and structural rearrangement of molybdic acid during heat treatment were studies by thermal analysis, X-ray diffraction, Raman and infrared spectroscopy. Thermal analysis indicates a two-step dehydration and formation of orthorhombic α-MoO3and monoclinic β-MoO3. Discharge profiles and kinetics of the materials are dependent on the amount of “structural water” into the host lattice. The electro-insertion of Li ions occurs mainly in two steps in the potential range between 3.0 and 1.5 V (compositional range 0<xLi<l.5). Kinetic measurement show that Li ions are highly mobile in the OHM framework. The partial molar quantities δGx, δSx, and δHx, estimated from EMF-temperature measurements and coulometric titration.
A Study of The Li|LixV2O4 Cell
Authors: Koval Eugen P. , Reshetnyak Olexander V. , Whittingham M. Stanley , Zavalij Peter Y. , Zavaliy Ihor Yu. 
Published: April 2011

ABSTRACTThe studies of the Li | 1M LiClO4 in propylene carbonate | LixV2O4 cell were carried out. The results of the electrochemical and X-ray investigations indicated that the cathode reaction in this cell proceeds as an intercalation process. Cycling test shows the reversibility of this cell along 35 charge/discharge cycles. However X-ray diffraction of the electrode material shows partial oxidizing of the LixV2O4 phase yielding γ-LiV2O5. The kinetic parameters of this process such as the chemical diffusion coefficient and mobility of lithium in the LixV2O4 were calculated.
Hybrid Materials Based on Conducting Organic Polymers and Electroactive Inorganic Molecules and Oxides. Application as Lithium-Insertion Electrodes
Authors: Lira-Cantu M. , Torres-Gomez G. , Gomez-Romero P. 
Published: April 2011

ABSTRACTThe synthesis, spectroscopic and electrochemical characterization of a series of hybrid organic-inorganic materials are reported. The hybrids are formed by conducting organic polymers (polyaniline, polypyrrole) and electroactive inorganic species. The latter can be either molecular anions (polyoxometalates, hexacyanoferrates) or extended oxide (V205), leading to different host-guest combinations. We have carried out a systematic study of the synthesis of the hybrids and determined key parameters for the reproducibility of the materials obtained. We have determined under what conditions the molecular species stay anchored in the polymer contributing to the overall electrochemical activity of these materials and turning the polymers from anion-insertion electrodes into cation-insertion electrodes. In the PAni/V2O5 system we have established the existence of two phases corresponding to the intercalation of one and two monolayers of PAni into V2O5 and have carried out their electrochemical characterization and their optimization as insertion cathodes in reversible lithium cells.
Investigation of Lithiated Carbons by Transmission Electron Microscopy and X-Ray Diffraction Analysis
Authors: Tran T. D. , Song X. Y. , Kinoshita K. 
Published: April 2011

ABSTRACTThe microstructures of lithiated synthetic graphite and carbon black were studied by high- resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analysis. Information about the crystal structure of carbon containing various Li compositions can provide useful insights to our understanding of the Li storage mechanism in carbonaceous materials. Samples with compositions of Li0.93C6or Li0.45C6 were found to contain both stage-one and stage-two compounds. These observations are consistent with XRD data. The changes in sample microstructure as the results of lithiation and exposure to electron irradiation were observed by TEM and recorded over several minutes in the microscope environment. Selected area electron diffraction patterns indicated that the lithiated samples quickly changed composition to LiC 24, which appeared to dominate during the brief analysis period. The layer planes in the lattice image of a disordered carbon black after Li insertion are poorly defined, and changes in the microstructure of these lithiated carbons was not readily apparent. Observations on these lithium intercalation compounds as well as the limitation of the experimental procedure will be presented.
Concept of Mismatch and Relaxation Derived from Conductivity Spectra of Solid Electrolytes
Authors: Funke K. , Wilmer D. 
Published: April 2011

ABSTRACTCrystalline ion conductors like RbAg4I5 and others display a characteristic shape of their dispersive conductivities at frequencies below the microwave regime. As the temperature is decreased, the onset of the dispersion is shifted to lower frequencies and thus the characteristic shape of the dispersion becomes visible in an increasingly broad frequency range. In a log-log plot of the frequency-dependent conductivity, the slope is found to increase continuously, but not to surpass unity. For the first time, this behavior is now consistently explained. The particular shape of the dispersion is shown to be equivalent to a proportionality of the rates of relaxation via the singleand many-particle routes. This is the essence of the concept of mismatch and relaxation (CMR). Model conductivity spectra based on the CMR include the UDR (universal dynamic response) as well as the NCL (nearly constant loss) behavior. Both universalities are thus traced back to a common dynamic origin.
Thermal and Electrical Properties of Li20-V205-TeO2Glassy System
Authors: Sanchez E. , Angell C. A. 
Published: April 2011

ABSTRACTOxide glasses had receive a great deal of attention on the last couple of years because of their potentially high cationic transport. Interesting features have been found on Li20-V205-TeO2glassy system. Such materials were prepared under open air at 800°C and traditional quenching. Glass formation was been found up to 45% alkali concentration on the V205-TeO2binary system. Upon addition of Li20 the glass transition temperature lowered systematically up to values near 175°C. Structural correlation between glass transition and structure are made. Those materials show high promise as electrolytes for solid-state batteries applications.
7Li NMR study of ionically conducting glasses
Authors: Akai Tomoko 
Published: April 2011

ABSTRACTTemperature dependence of 7Li NMR was measured in 50Li20-50B203 glasses. A new method for the analysis of motional narrowing of the line width (MNLW) incorporating Kohlrasuch-Williams-Watt (KWW) function, exp(-(t/τ)β) is presented. The obtained activation parameters are compared with that from conductivity. It was shown that MNLW can be explained by the same activation energy from conductivity. It was found that electrical relaxation time was an order of magnitude smaller than that from those from NMR line width. At high temperature region, where the line is well narrowed, a residual line width was observed. It is as large as 1 kHz, and gradually decreases with the increase in temperature. It was explained that there is a mobility difference in lithium ions in this glass. These results suggest that some fraction of ions are highly mobilized in the glass.
Conductivity Enhancement of Solid Ionic Conductors (CuBr, LiI) with Dispersed Oxide Particles (TiO2, A1203) : Experiments and Percolative Transport Model
Authors: Albinet G. , Debierre J.-M. , Knauth P. 
Published: April 2011

ABSTRACTThe electrical conductivity of two-phase mixtures of an ionic conductor with dispersed insulator particles is described using a percolative transport model. The difference of grain sizes, the existence and anisotropy of confined high conductivity paths near the grain interfaces are implemented by simple rules. The model is capable of simulating the two cases of ionic conductor/insulator composites : those with and those without strong interfacial interactions. The discussed experimental examples are LiI-A1203, CuBr-A1203 and CuBr-TiO2.
Mixed Ionic and Electronic Conduction in Mn/Mo Doped Gadolinium Titanate
Authors: Sprague J.J. , Tuller H.L. 
Published: April 2011

ABSTRACTRecent work has shown that Gd 2(Ti1−xMOx)2O7 (GT-Mo) exhibits high levels of mixed conduction under reducing atmospheres, making it suitable as an anode in a solid oxide fuel cell, but not as a cathode since it decomposes at high Po2. We have succeeded in extending the stability limits of GT-Mo to higher Po2 with the addition of Mn. Our earlier studies on Gd2((MoyMn1−y)xTi1−x)2O7 (GMMT) as a function of Po2,T, and composition utilizing impedance spectroscopy and x-ray diffraction are extended to include a wider range of compositions (x ≤ 0.3). In addition, a new sintering method for the GMMT material is introduced that compensates for observed materials loss and abnormal conduction behavior in previous studies. Defect models explaining the dependence of the conductivity on oxygen partial pressure, temperature, and composition are presented as well.
Electrode Kinetics of Porous La0.5Sr0.5Co0.8Ga0.2O3-δ
Authors: Yang Yuemei L. , Jacobson Allan J. 
Published: April 2011

ABSTRACTLSCGO (La0.5Sr0.5Co0.2Ga0.2O3−δ) was selected and synthesized as a cathode material for gallate-based solid oxide fuel cells (SOFC). In the present paper, the electrode polarization behavior of LSCGO was studied under various pO2and temperature conditions by a two-probe ac impedance method. A symmetric electrochemical cell: pO2, LSCGOILSGMOILSCGO, pO2, where the composition of the electrolyte LSGMO is La0.8Sr0.2Ga0.85Mg0.15O3−δ, was used in the study. Below 600°C, only semicircles due to bulk and grain boundary contributions were observed. In temperature range 700-800°C, however, a depressed and asymmetric semicircle was found in the low frequency regime (1 mHz to 1000 Hz). This low frequency feature in the impedance spectra is attributed to the electrode polarization process and can be fitted to the well-known Gerischer impedance equation. The resulting fitting parameters are used to derive surface exchange and bulk diffusion coefficients.
Conductivity Relaxation Studies On La0.5Sr0.5Co0.8Ga0.2O3−δ
Authors: Wang S. , Abeles B. , Jacobson A.J. 
Published: April 2011

ABSTRACTThe surface exchange coefficient, ki, of the mixed ionic electronic conductor perovskite, La0.5Sr0.5Co0.8Ga0.2O3−δ, was determined in the temperature range 600-900°C by electrical conductivity relaxation on thin plate and long bar samples, using four probe dc conductivity measurements. The normalized conductivity could be fitted by the equation corresponding to surface limited relaxation, (σ(t) − σ1) / (σ2 − σ1) = 1 − exp(−t / Tr), where τ = l1l2 / [(l1 + l2)Γki], σ(t), σ1 and σ2 are the time dependent, initial and final conductivities, Γ is the thermodynamic factor and 21, and 212 are the lateral sides of the bar. Numerical simulation shows that the shape of the relaxation curve for the plate geometry changes only little in going from surface limited to diffusion limited transport, the change is significantly larger for the bar geometry.
Oxygen Transport in the Sr2Fe3−x, CoxOySystem
Authors: Ma B. , Balachandran U. , Mitchell B.J. , Richardson J.W. , Hodges J.P. , Jorgensen J.D. 
Published: April 2011

ABSTRACTThe mixed-conducting Sr-Fe-Co oxide has potential use as a gas separation membrane. Its superior oxygen transport reveals the feasibility of using oxide membranes in large-scale oxygen separation. Sr2Fe3-xCoxOy(with x = 0.0, 0.3, 0.6, and 1.0) samples were made by solid state reaction. To understand the oxygen transport mechanism in this system, conductivity and thermogravimetry experiments were conducted at high temperature in various oxygen partial pressure environments. The oxygen diffusion coefficient was determined from the time relaxation transient behavior of the specimen after switching the surrounding atmosphere. Mobility of the charge carrier was derived from relative conductivity and weight changes. X-ray diffraction experiments were carried out on these samples to determine their crystal structures.
Synthesis of SrRuO3 by Sol-Gel Processing
Authors: Wu Y. , Zamani S. , Cao G. Z. 
Published: April 2011

ABSTRACTElectronic conductive oxide SrRuO3has been synthesized by sol-gel processing. Various precursors were tested and four different processing methods were developed. Stable SrRuO3sols were obtained using these four processing methods with various precursors. It was found that partial hydrolysis of strontium precursors was required to achieve a cross-condensation of ruthenium and strontium, so as to obtain a single phase SrRuO3perovskite at relatively low temperatures. The stable sols were either poured into petri-dishes to form xerogels or dip-coated on substrates to form thin films. Single phase SrRuO3perovskite was obtained after heat-treatment at 800 °C or higher temperatures. TGA/DTA, XRD and SEM were applied to characterize sol-gel derived SrRuO3ceramic powders and films.
Electrical Conductivity of Zirconia-Mn Oxide Mixture
Authors: Kim J. H. , Choi G. M. 
Published: April 2011

ABSTRACTMn2O3 was added to YSZ (8 mol% yttria- doped zirconia) either to form solid solution or two-phase (Mn2O3 and Mn2O3 doped-YSZ) mixed-conducting oxide. The electrical conductivity was measured between 600 and 1000°C in air using 4-probe d.c. method in a wide composition range to determine composition-dependent conductivity. Up to 12 mol% MnO1.5 addition, the conductivity decreases and the activation energy increases. With further increase of MnO1.5 content, the conductivity of composite begins to increase slowly and then increases rapidly after 30 mol% due to the interconnected, conductive Mn2O3 particles. Above 35 Mol% MnO1.5 content, the activation energy is nearly the same as that of Mn2O3. Hysteresis behavior shown in the conductivity of composite also provides the evidence of percolation by MnO1.5.