bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrogen Storage in Titanium-Magnesium-Nickel Mixtures
Authors: Lomness Janice K. , Hampton Michael D. , Giannuzzi Lucille A. 
Published: April 2011

ABSTRACTThe hydrogen interaction properties of mechanically alloyed mixtures of Ti, Mg, and Ni have been shown to be strongly dependent on the time and energy of ball milling. Mixtures ball milled at a ball to powder ratio (by mass) of 20:1 were able to absorb 3–4 wt% hydrogen. Mixtures ball milled at a ball to powder ratio of 70:1 were able to absorb up to 11 wt% hydrogen. The dependence of hydrogen uptake on ball milling time and energy is shown to be related to the microstructural morphology of the ball milled powders. The original Mg powder particles were heavily deformed by the ball milling process and contained nano-sized inclusions of both Ti and Ni at the surface. The higher energy ball milled samples showed a more refined microstructure and a greater hydrogen capacity. In addition, there was an inverse relationship between the amount of hydrogen uptake and the size of inclusions at the surface of the particles.
Soft X-Ray Emission and Resonant Inelastic X-Ray Scattering Studies of Transition Metal Oxides.
Authors: Smith Kevin E. , McGuinness Cormac , Downes James , Ryan Philip , Fu Dongfeng , Hulbert Steven L. , Honig J.M. , Egdell Russel 
Published: April 2011

ABSTRACTThis paper discusses the application of soft x-ray emission and resonant inelastic x-ray scattering as probes of the electronic structure of transition metal oxides. The results of studies on the narrow gap insulator CdO, and the Mott-Hubbard oxide Cr-doped V2O3, are reported. The O 2p valence band partial density of states for CdO has been measured, and emission due to the hybridization of the O 2p valence band states with Cd 4d shallow core level has been observed. For Cr-doped V2O3, the temperature induced metal-insulator transition in samples with 1.5% Cr was observed using soft x-ray emission, and both charge transfer and dipole forbidden d-d excitations were observed using resonant inelastic x-ray scattering.
Rules for Understanding and Designing Novel Molecule-Based Rare-Earth Magnetic Compounds
Authors: Roy Lindsay E. , Hughbanks Timothy 
Published: April 2011

ABSTRACTResults of SDFT calculations were used to construct and check features of a generally applicable qualitative approach to understanding magnetic coupling in rare-earth-rich compounds. Using fragments based on structures of metal-rich lanthanide compounds, we have investigated molecular and low-dimensional extended structures, including Gd3I6(OPH3)12, Gd6I12Co(OPH3)6, and Gd2Cl3. Open-d-shell clusters facilitate strong ferromagnetic coupling whereas in the closed-d-shell systems prefer antiferromagnetic coupling. The f-d exchange interaction, mediated by spin polarization of both filled and partially-filled metal-metal bonding orbitals, was described for the model system Gd3I6(OPH3)12n+ using basic perturbation methods. This method has been successful for predicting the magnetic ground state for models of Gd[Gd6I12Fe] and Gd2Cl3.
Synthesis of [Ca2(Co1-xCux)2O4] yCoO2 Single Crystals and Their Intrinsic Properties
Authors: Suzuki M. , Horii S. , Sano M. , Fujie K. , Otzschi K. , Shimoyama J. , Kishio K. 
Published: April 2011

ABSTRACTThin plate-like [Ca2(Co1-xCux)2O4] y CoO2 single crystals were successfully grown by the flux method using SrCl2 solvent. The largest crystal size was approximately 3 × 3 × 0.01 mm3. The copper concentrations, x, in the crystals were found to be depending on each crystal, suggesting a certain solid-solution range of copper in the present system. The obtained crystal showed low resistivity (∼4.3mQcm) and high Seebeck coefficient (∼160μVK-1) at 300K. The crystal showed anisotropic magnetization with larger magnetization under H ∥ c. Irreversible magnetization behavior below ∼90K was also found under H ∥ c.
Electromagnetic and Thermoelectric Characteristics of NaxCoO2 of Precisely Controlled Na Nonstoichiometry
Authors: Motohashi Teruki , Karppinen Maarit , Yamauchi Hisao 
Published: April 2011

ABSTRACTElectromagnetic and thermoelectric characteristics of a sodium-cobalt oxide, NaxCoO2, were investigated. A precise control of Na nonstoichiometry was successfully facilitated by an unusual synthesis method named “rapid heat-up” technique. With increasing x, the absolute value of resistivity (ρ) monotonically decreased, while the value of thermoelectric power (S) increased, giving rise to a drastic enhancement in the thermoelectric power factor, i.e. S2 / ρ. Simultaneously enhanced thermoelectric power and reduced resistivity of the present compound are difficult to be understood within the framework of a conventional band picture. Moreover, for samples with the solubility limit Na content, i.e. x = 0.75, we discovered an unconventional electronic transition at Tm = 22 K, which may be induced by the strong-correlation effect of 3d electrons.
Synthesis and Lattice Distortion of Ferroelectric/Antiferroelectric Bi(III)-containing Perovskites
Authors: Inaguma Yoshiyuki , Miyaguchi Atsushi , Katsumata Tetsuhiro 
Published: April 2011

ABSTRACTBi(III)-containing perovskites Bi1/2Ag1/2TiO3and Bi(M1/2Ti1/2)O3(M= Co, Mg, and Ni) were synthesized under oxygen pressure as high as approximately 1 MPa and under a pressure as high as 6 GPa, and the lattice distortions were investigated. It was found that ferroelectric Bi1/2Ag1/2TiO3may be rhombohedrally distorted. In constrast, Bi(M1/2Ti1/2)O3(M= Co, Mg, and Ni), the structure of which is different from GdFeO3-type compound, is monoclinically distorted. The ratio of lattice parameters of the monoclinic perovskite-subcell for Bi(M1/2Ti1/2)O3(M= Co, Mg, and Ni),am/bmis larger than that of GdFeO3-type perovskites, though the tolerance factor is close. In addition, it was found that Bi(Ni1/2Ti1/2)O3undergoes a first-order phase transition from a GdFeO3-type phase(high-temperature phase) at around 490 K. These results indicate that the Bi3+character in Bi(III)-containing perovskites strongly influences the structure distortion.
Reinvestigation of the Incommensurate Structure of αPbO.
Authors: Baldinozzi Gianguido , Raulot Jean-Marc , Petricek Vaclav 
Published: April 2011

ABSTRACTLead monoxide exists at room temperature in two forms, namely α-PbO, litharge (red, tetragonal) and β3-PbO massicot (yellow, orthorhombic). The weak bonds along the c axis and the ferroelastic nature of the incommensurate phase prevent the growth of single crystals suitable for high quality diffraction techniques (very small ferroelastic domains and frequent stacking faults in these layered structures). A structural determination of the incommensurate structure was proposed in the superspace group C2mb(0β;0) using the integrated intensities extracted from powder diffraction patterns. More recently an electron microscopy study suggested the existence of systematic extinctions affecting the satellite reflections and it supports the more symmetric space group Cmma(0β0)s. In this paper, high resolution powder diffraction patterns (synchrotron) were refined in the incommensurate phase using the Rietveld method. Various superspace groups and forms for the modulated displacements were tested. The consequences of this structural model on the electronic structure are analysed using also ab-initio calculations.
Commensurate-incommensurate phase transition in charge ordered La1-xCaxMnO3 by single crystal diffraction and electron imaging
Authors: Tao Jing , Murakami Y , Zuo Jian-min 
Published: April 2011

ABSTRACTElectron nanodiffraction from single crystal domain of La1-xCaxMnO3 with 0.5 ≤ × ≤ 0.8 is carried out to study the charge ordering phase transition in this system. The melting processes of charge ordering structure in samples with x = 1/2, 2/3 and 4/5 are observed in-situ by increasing temperature from 93K – 298K. During the phase transition, electron diffraction results show that the nearly commensurate low-temperature charge ordering structure continuously evolves to incommensurate structure with directly decreasing sizes of charge ordered area. The picture of this phase transition is confirmed by the real space imaging. The real space images clearly show the introduction of charge ordering defects during the melting process in this sample.
Epitaxial Growth of Magnetic Nickel Nanodots by Pulsed Laser Deposition
Authors: Zhou H. , Kumar D. , Kvit A. , Tiwari A. , Narayan J. 
Published: April 2011

ABSTRACTEpitaxial nickel magnetic nanodots were obtained by pulsed laser deposition (PLD) technique on Si (100) substrate using epitaxial TiN film as the template. Characterization methods include: high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) Z-contrast imaging, selected area electron diffraction (SAD), and X-ray diffraction (XRD) techniques. The results showed that as long as no coalescence between neighboring dots occurred, the dots are all single crystal. The predominant orientation relationship observed is Ni (100) // TiN (100) // Si (100), the so-called “cube-on-cube” orientation relationship. Other rotational orientation relationships, where the nickel crystal rotates an angle with respect to TiN (011) directions, were also observed. The dots are in faceted island shapes, bounded by (111) and (001) facets. The actual size of dots varies from a few nanometers to tens of nanometers, depending on the deposition time and temperature. The shape of a certain dot was found to be closely related to its epitaxial orientation. Effects of deposition temperature and template crystalline quality were studied. It was found that deposition temperature in a certain range does not have much influence on the epitaxial orientation of dots, while the crystalline quality of titanium nitride (the underlying template) is primarily responsible for the orientation variation. At the optimum condition, samples with a large fraction of cube-on-cube orientated nickel dots could be obtained in a rather wide temperature range (up to 250 °C), as evidenced by the strong reflections from both SAD and XRD. Samples containing more than one layer of nickel and titanium nitride matrix were also studied. The results showed that the degree of orientation perfection could be greatly improved by decreasing the size of dots.
Solid State Synthesis and Characterization of Tin-Based Low-Dimensional Materials
Authors: Salami Tolulope O. , Oliver Scott R. J. 
Published: April 2011

ABSTRACTWe report the synthetic conditions, physical properties and potential applications of late group 14 metal (Sn) 0D, 1D, 2D and 3D extended materials. The structures are primarily neutral chain and anionic layered compounds. The latter are charge-balanced by ammonium cations, as in and BING-7 [Sn(C2O4)F-] [NH4+] and BING-8 [Sn(PO4H)F-] [NH4+]. The neutral layered compound and chain compounds BING-1 [Na4Sn4(C2O4)F6], BING-2 [KSn(C2O4)F] and BING-4 [Sn(C2O4)(C5H5N)] have also been synthesized solvothermally. Thermogravimetric analysis (TGA) under nitrogen and in-situ variable temperature X-ray diffraction show that the materials decompose in the 200°C to 300°C range to more stable phases. Nuclear magnetic resonance (NMR) was used to monitor the ion-exchange properties of some of the materials. The intercalation properties of these materials are still being investigated.
The Ternary System Li2O – Sb2O5 – CuO
Authors: Castellanos R María A. , Trujillo Tovar S. 
Published: April 2011

ABSTRACTSubsolidus compatibility relations in the ternary system Li2O – Sb2O5 – CuO have been determined. One new copper-rich phase, LiCu4SbO7, W, and one new solid solution series, Li1-xSb1-xCu3xO3, over the composition range 0 < × ≤ 0.077 have been prepared. Eight triangles of compatibility were determined at (approximately) 1000 °C.
Na+/H+ Topotactic Exchange on NaNbWO6 with TTB-like Structure: The series HxNa1-xNbWO6
Authors: Kuhn A. , García-Alvarado F. , Bashir H. , Dos Santos A. L. , Acosta J. L. 
Published: April 2011

ABSTRACTTTB-type NaNbWO6 has been used to perform sodium-proton exchange reactions by using nitric acid as an exchanging agent. The characterisation of the exchange reaction products, performed by means of chemical analysis, X-ray diffraction and thermogravimetric analysis, indicate that the exchange reaction takes place topotactically. The following formula is proposed for the obtained phase of variable composition: Na1-xHxNbWO6 (0<x<0.46).
Synthesis of a Metallic Ceramic -Ti3SiC2 by PDS Process and its Properties
Authors: Sun ZhengMing , Hashimoto Hitoshi , Zhang ZheFeng , Yang SongLang , Abe Toshihiko 
Published: April 2011

ABSTRACTPowder mixtures of Ti/Si/C, Ti/SiC/C, Ti/Si/TiC, Ti/SiC/TiC and Ti/TiSi2/TiC were used for the synthesis of Ti3SiC2 by using a pulse discharge sintering (PDS) process. The Ti/Si/TiC powder was found to be the best among the five powder mixtures for the Ti3SiC2 synthesis. The highest content of Ti3SiC2 can be improved to about 99wt% at the sintering temperature of 1300°C for 15 minutes. The relative density of all the synthesized samples is higher than 98–99% at the sintering temperature above 1275°C. The nearly single phase Ti3SiC2 was found to show plastic deformation at room temperature and a good machinability. Both electrical and thermal conductivity were found to be more than two times of the value of a control pure Ti sample. The high-temperature mechanical tests confirmed that the Ti3SiC2 samples synthesized by the PDS process displayed a comparable performance with those fabricated by the other techniques.
Thin Films of Titanium Dioxide Prepared by Chemical Routes using Novel Precursors
Authors: Shalini K. , Chandrasekaran S. , Shivashankar S.A. 
Published: April 2011

ABSTRACTNovel, volatile, stable, oxo-β-ketoesterate complexes of titanium, whose synthesis requires only an inert atmosphere, as opposed to a glove box, have been developed. Using one of the complexes as the precursor, thin films of TiO2 have been deposited on glass substrates by metalorganic chemical vapor deposition (MOCVD) at temperatures ranging from 400°C to 525°C and characterized by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. All the films grown in this temperature range are very smooth; those grown above 480°C consist of nearly monodisperse, nanocrystals of the anatase phase. Optical studies show the bandgaps in the range 3.4–3.7 eV for films grown at different temperatures. Thin films of anatase TiO2 have also been grown by spin-coating technique using another ketoesterate complex of titanium, demonstrating that the newly developed complexes can be successfully used for thin film growth by various chemical routes.
Designing Crystal Structures from Atoms up
Authors: Derakhshan Shahab , Dashjav Enkhtsetseg , Kleinke Holger 
Published: April 2011

ABSTRACTA novel structure map was developed for metal-rich pnictides and chalcogenides M2Q, with M being an element of groups 3 – 5, and Q of groups 15 – 16. To date, this family exhibits eleven different structure types, which are separated in well-defined domains in this structure map. The map comprises a combination of atomic factors as the abscissa, namely principal quantum numbers, valence-electrons, and radii, and a structural factor as the ordinate, which is the averaged coordination number of the Q atoms. We demonstrate in this contribution how this new map can be and has been used to predict crystal structures of new materials from atoms up. First attempts to expand this concept towards different stoichiometries are described.
Proton conductivity of functionalized zirconia colloids
Authors: Carrière D. , Moreau M. , Lahlil K. , Barboux P. , Boilot J.-P. 
Published: April 2011

ABSTRACTColloidal 60 nm ZrO2 particles have been treated with aqueous solutions of phosphoric acid and sulphophenyl-phosphonic acid (SPPA). This leads to the covalent bonding of P-OH and C6H4-SO3H acid groups onto the surface of the particles. The resulting acidity yields a significant proton conductivity at the surface of the particles.The proton conductivity of the ZrO2-H3PO4 system is quite stable against a change of relative humidity and temperature. However, it remains limited by the low acidity of the POH group. On the contrary, the proton conductivity of the ZrO2-SPPA system is almost two orders of magnitude higher at high relative humidities due to the high acidity of the C6H4-SO3H group (1.10-3 S.cm-1 in the same conditions). But, it is much more sensitive to changes in relative humidity.A mixed grafting of both H3PO4 and SPPA onto the zirconia particles allows to obtain a conductivity as high as in the SPPA case whereas it remains stable with humidity and temperature as for the phosphoric acid. This probably indicates that the conductivity arises from ionization of sulphonic acid but that the weaker phosphoric acid groups contribute to the conduction mechanism.
Electrical Conductivity in Praseodymium-Cerium Oxide
Authors: Stefanik Todd S. , Tuller Harry L. 
Published: April 2011

ABSTRACTThe electrical conductivity of PrxCe1-xO2-δ (PCO) for 0 ≤ × ≤ 0.20 was examined over a wide range of temperatures and oxygen partial pressures. A defect model based on multiple Pr valence states was found to be qualitatively consistent with the observed data. A unique pO2-dependent ionic conductivity is observed at high pO2 values in compositions containing low levels of Pr (0 ≤ × ≤ 0.01). In compositions containing higher amounts of Pr (0.05 ≤ × ≤ 0.20), formation of a Pr induced impurity band results in a significant electronic conductivity at high pO2 values.
The Synthesis and Characterisation of Ge Containing Apatite-Type Oxide Ion Conductors
Authors: Slater P. R. , Sansom J. E. H. , Tolchard J. R. , Islam M. S. 
Published: April 2011

ABSTRACTApatite-type oxides, La10-x(Si/Ge)6O26+z, have been attracting significant interest recently due to their high oxide ion conductivities. Most of the work so far has focused on the Si based systems, since the Ge based systems suffer from problems attributed to Ge loss. In this paper we show that doping divalent cations on the La site or B on the Ge site helps to stabilise the hexagonal apatite lattice for these Ge based systems. These doped phases show high oxide ion conductivities, although results from extended sintering studies suggest that Ge loss is still a problem. In order to limit Ge loss, we have also examined Bi doping to lower the sintering temperature and preliminary results for the novel Bi containing apatite-type phases, La6Bi2M2Ge6O26 (M=Mg, Sr, Ba) and La8-xBi2Ge5GaO26+y, are also reported.
Phase Stability of Beta-gallia Rutile Intergrowths: (Ga,In)4(Sn,Ti)n-4O2n-2
Authors: Charoenwongsa Malin , Edwards Doreen D. 
Published: April 2011

ABSTRACTBeta-gallia-rutile (BGR) intergrowths possess one-dimensional tunnels that are suitable hosts for small-to-medium cations, thereby making them potential candidates for ion conductors, ion separators, battery electrodes, and chemical sensors. The BGR intergrowths are a series of homologous compounds expressed generically as Ga4Mn-4O2n-2, where n is an integer; and M is a tetravalent cation that forms a rutile-type oxide. In an attempt to identify materials with high tunnel densities and higher contents of a reducible M4+ cation, we are mapping the compositional stability regions of intergrowths expressed as Ga4–4xIn4xSn(n-4)(1-y)Ti(n-4)yO2n-2 where n = 6, 7 and 9 and 0.15 < x < 0.30 and 0 < y < 1.0. Polycrystalline samples were prepared by solid-state reaction at 1250 – 1400 °C and characterized by X-ray diffraction. Factors that affect phase stability are discussed.
Study of bare and functionalized Zirconia Nanoparticles Filled Polymer Electrolytes Based on a Polyurethane
Authors: da Conceição Paulo V. S. , Faria Luiz O. , Santos Adelina P. , Furtado Clascídia A. 
Published: April 2011

ABSTRACTIn this work, composite polymer electrolytes based on a thermoplastic polyurethane/LiClO4 amorphous system and on bare and functionalized zirconia nanoparticles as a filler are reported. The ceramic nanoparticles were synthesized via the sol-gel route using zirconium butoxide as the precursor for zirconium oxide nanoclusters and methacrylic acid as an organic modifier group. The salt concentration in the polymer phase was 17 wt% and fillers were added in the range between 2 and 10wt%. Scanning electron microscopy (SEM) was used to characterize the average size and the homogeneity of the nanoparticles in the polymer matrix, while impedance spectroscopy (IS) was used to evaluate the ionic conductivity of the composites. The addition of zirconia fillers results in an increase in ionic conductivity for all filled systems. The results also show that the functionalization of the zirconia nanoparticles promotes a significant increase in conductivity, suggesting that the interaction of the metracrylate-functionalized fillers with the polyurethane matrix was greatly improved. These results raise interest in the study of organically modified ceramic clusters as fillers for electrolyte polymers.
Cation Ordering in Substituted LiMn2O4 Spinels
Authors: Strobel P. , Ibarra-Palos A. , Poinsignon C. 
Published: April 2011

ABSTRACTIn order to overcome the capacity fading of LiMn2O4 in lithium batteries, various substitutions for Mn have been proposed. The structural implications of substitution in LiMn2-xMxO4 with x = 0.5, i.e. with exactly 1/4 octahedral (16d-site) cations replaced, are investigated here. For this stoichiometry, cationic ordering was known previously for M = Mg and Zn, resulting in a superstructure with primitive cubic symmetry. Given the poor chemical contrast of X-ray diffraction between Mn and Co, Ni or Cu, LiMn1.5M0.5O4 samples were studied by neutron diffraction and IR spectroscopy. Both techniques show the occurence of cationic ordering for M = Ni and Cu, but not for Co or Ga. In the case of M = Zn, further complication due Li/Zn ordering on the tetrahedral (8a) site is well resolved by FTIR. This investigation shows that the main driving force for octahedral cation ordering is the charge difference between Mn and M atoms.
Enhanced Ionic Conduction Observed for Ordered-Mesoporous Alumina-Ionic Conductor Composites
Authors: Maekawa Hideki , Tanaka Ryo , Yamamura Tsutomu 
Published: April 2011

ABSTRACTOrdered-mesoporous Al2O3 was synthesized by the sol-gel method using neutral surfactants as templates. The pore size can be controlled over the range of 2.8∼12.5 nm by using different surfactant copolymers and by different synthetic conditions. By utilizing cyclohexane as a co-solvent, mesoporous Al2O3 having relatively mono-dispersed particle size was obtained. Composites composed of the synthesized mesoporous Al2O3 and the lithium ion conductor (LiI) was prepared. The dc electrical conductivity of 50LiI ·50(mesoporous Al2O3) was 2.6×10-4 S cm-1 at room temperature, which is more than 100 times higher than that of pure LiI. The pore size dependence of the conductivity of LiI-mesoporous Al2O3 composite was examined. A systematic dependence of conductivity upon pore size was observed, in which the conductivity increased with decreasing the pore size.
Ball-milling: an alternative way for the preparation of anodes for lithium-ion batteries
Authors: Guérard Daniel , Janot Raphaël 
Published: April 2011

ABSTRACTThe preparation of new anodic materials for lithium-ion batteries is possible by ball-milling within liquid media. Those powders can be as diverse as: highly anisometric graphite particles (geometrical anisotropy around 100), graphite-maghemite (γ Fe2O3) composites and graphite-intercalation compounds with high lithium contents (e.g. LiC3 is obtained by ball-milling of Li + 2C powders). These phases are the first superdense graphite-lithium compounds stable under ambient pressure and lead to a capacity of 1 Ah/g as primary battery and 370 mAh/g as secondary one. The synthesis and characterizationschemical analysis, XRD, pycnometry, TEM, SEM, 7Li NMR, magnetic measurements) are presented for each materials as well as the electrochemical behavior.