bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cohesive Properties of PuGa Alloys
Authors: Robert Gregory , Colinet Catherine , Siberchicot Bruno , Pasturel Alain 
Published: April 2011

ABSTRACTWe present results on the structural stability of PuGa alloys based on the local spin-density approximation and including non-local corrections to the exchange-correlation functional. We use the projector augmented wave (PAW) method to calculate the formation energies of five intermediate phases. The stability of the δ solid solution is analysed using selected supercells for total energy caclulations. Cluster variation calculations in the tetrahedron approximation are performed to study the effect of composition and of finite temperature on the ordering phenomena in the δ solid solution. The Pu-rich part of the Pu-Ga phase diagram is computed.
SIC-LSD study of δ-Pu and PuO2±x
Authors: Petit L. , Svane A. , Szotek Z. , Temmerman W. M. 
Published: April 2011

ABSTRACTThe electronic structures of actinide solid systems are calculated using the self-interaction corrected local spin density approximation. Within this scheme the 5f electron manifold is considered to consist of both localized and delo-calized states, and by varying their relative proportions the energetically most favourable (ground state) configuration can be established. Specifically, we discuss elemental Pu in its δ-phase, and the effects of adding O to PuO2.
Uranium (and Cerium) Compounds At High Pressures and Magnetic Fields
Authors: Cornelius Andrew L. , Kumar Ravhi S. , Light Brian E. 
Published: April 2011

ABSTRACTCorrelated-electron systems are so named due to strong interactions between electrons unlike traditional metals (e.g. copper) that have “free electrons” that interact very weakly. Knowledge of the Fermi surface, density of electron states and band structure are the starting points for a first-principles understanding of the electronic and electronically related macroscopic properties, e.g. equation of state. The use of high pressure and high magnetic fields to alter the electron-electron (hybridization) and electron-lattice interactions give us powerful tools to understand complicated rare earth and actinide correlated-electron systems and allows precise testing of experiment to theory. Correlated-electron systems yield a wide variety of ground states that are a direct result of the hybridization strength including: short and long range magnetic order, spin fluctuating, enhanced Pauli paramagnetism, heavy fermion behavior and superconductivity. We will review some results on U compounds in high magnetic fields and high pressures. By comparing the results to Ce compounds that have significantly more localized f electrons, the effect of direct 5f electron wavefunction overlap in U compounds can be discerned. Consequences on the search for U based heavy fermion superconductors will be discussed.
High Throughput Screening of Materials for Solid Oxide Fuel Cells
Authors: Lemmon John P. , Manivannan Venkatesan , Jordan Tracey , Hassib Lamyaa , Siclovan Oltea , Othon Michelle , Pilliod Mile 
Published: April 2011

ABSTRACTState of the art commercial cathodes for solid oxide fuel cells (SOFC) include LaMnO3 with a zirconia-based electrolyte. However, the vacancy concentration in A site doped LaMnO3 is low, thus ionic conductivity is also very low (10−7 – 10−8 S/cm at 800 °C). The surface path dominates the reaction rate of the LaMnO3 cathode; therefore the optimized electrode is a porous composite material of both the cathode material and electrolyte and relies on triple-point boundaries for performance. The electrical conductivity and thermal expansion properties of this cathode material and other A3+B3+O3 perovskites can be tuned by substitution at the A and/or B site. The numerous combinations of composition, processing and microstructure needed for improved cathode performance is well suited for a high throughput screening (HTS) approach towards optimization and discovery. We present here a high throughput discovery process that includes, synthesis, performance testing and characterization techniques directed towards new low temperature SOFC cathode materials.
Combinatorial Chemical Vapor Deposition of Metal Silicate Films Using Tri(t -butoxy) silanol and Anhydrous Metal Nitrates
Authors: Zhong Lijuan , Chen Fang , Campbell Stephen A. , Gladfelter Wayne L. 
Published: April 2011

ABSTRACTA modified low-pressure chemical vapor deposition reactor was used to create compositional spreads of MO2/SiO2 films (M = Hf, Zr and Sn) using tri(t-butoxy) silanol and anhydrous metal nitrates of hafnium, zirconium and tin at temperatures below 250 °C. The compositional spreads formed by this process were characterized by ellipsometry and Rutherford backscattering spectrometry. A survey of possible reactions involved in the deposition is included.
Combinatorial Fabrication and Studies of Small Molecular Organic Light-Emitting
Authors: Li Devices G. , Zou L. , Cheon K. O. , Shinar J. 
Published: April 2011

ABSTRACTVarious combinatorial matrix arrays of UV-violet, white, and blue-to-red organic light-emitting devices (OLEDs), fabricated using a sliding shutter technique, are described. In the UV-violet devices, which contain a UV-violet emitting layer of 4,4′-bis(9-carbazolyl) biphenyl (CBP), the optimal radiance R and external quantum efficiency ηext were determined with respect to the thicknesses of the hole transporting layers. In the blue-to-red devices, which contained a blue-emitting layer of 4,4′-bis(2,2′-diphenyl-vinyl) -1,1′-biphenyl (DPVBi) and a red-emitting 5 wt.% dye-doped guest-host layer, the color of the devices evolved continuously from blue to red as the thickness of the doped layer increased from 0 to 35 Å. The (nominal) 2 Å-thick doped layer device exhibited the highest brightness L ∼ 120 Cd/m2 and external quantum efficiency ηext ∼4.4 % at a current density of 1 mA/cm2. In the white OLEDs, which were similar to the blue-to-red devices but with lightly doped emission layer, the highest brightness Lmax was over 74,000 Cd/m2; in all devices Lmax exceeded 50,000 Cd/m2. The maximum efficiencies were 11.0 Cd/A, 5.96 lm/W and 4.6% at 5.8 V, 0.6 mA/cm2, and 68 Cd/m2 in a 0.25 wt.%, 2 nm-thick doped layer device.
Characterization of Soluble Polymer Supported Organic Molecules by Mass Spectrometry
Authors: Enjalbal C. , Lamaty F. , Ribière P. , Varray S. , Suberchicot E. , Yadav-Bhatnagar N. , Martinez J. , Aubagnac J-L. 
Published: April 2011

ABSTRACTSyntheses carried out on soluble polymers, such as polyethylene glycol (PEG), benefit the advantages of both solution-phase and solid-phase syntheses. The choice of the reaction solvent governs the polymer solubility. Synthetic steps are conducted under homogeneous conditions whereas purifications are performed by filtration after polymer precipitation. This alternative strategy, known as liquid-phase chemistry, has been investigated to prepare combinatorial libraries.The fact that soluble polymer supported molecules are directly amenable to standard spectroscopic methods, including NMR (1H, 13C) and ESI or MALDI mass spectrometry (ElectroSpray and Matrix Assisted Laser Desorption Ionization) allows to perform to in situ reaction monitoring without the need to release the compound from the polymeric support.We report a general methodology to characterize step by step soluble polymer supported organic molecules by MALDI and ESI mass spectrometry. High throughput analyses were targeted to fullfil combinatorial chemistry requirements. Data acquisition and interpretation were automated through the design of specific experimental protocols and a data managment software. MALDI mass spectrometry was appropriate to analyze pure supported molecules whereas ESI mass spectrometry coupled to liquid chromatography was required to unravel PEG mixtures.
Nonequilibrium Structures in Codeposited Cr-Fe-Ni Films
Authors: Specht E.D. , Rack P.D. , Rar A. , Pharr G.M. , George E.P. , Hong H. 
Published: April 2011

ABSTRACTTernary libraries are prepared by codeposition of Cr, Fe, and Ni on single-crystal Si and Al2O3 (sapphire) substrates at ∼100°C. The varying proximity to the three metal sources produces a spread of compositions in the films, which are analyzed both as-deposited and after annealing in vacuum for 2 h at 500°C. Structural maps are produced using synchrotron radiation and simultaneous detection of 2D diffraction patterns and x-ray fluorescence spectra. Four phases are identified in the as-deposited films. Three phases occur in equilibrium: bcc (α), fcc (γ), and intermetallic (σ). The fourth phase does not correspond to any equilibrium phase in the Cr-Fe-Ni system; it is tentatively identified as isomorphic to the α-Mn (A12) structure. After annealing, the nonequilibrium phase is no longer observed, but the occurrence of the three equilibrium phases is still far from the equilibrium phase boundaries. The particle size measured by x rays is small (9–15 nm), suggesting that higher annealing temperatures are required for the growth of equilibrium phases.
Combinatorial Study and High Throughput Screening of Transparent Oxygen and Moisture Barrier Films
Authors: Grunlan Jaime , Chavira Aaron , Wolfe Timothy J. , Akhave Jay , Hamilton Charles , Mehrabi Ali R. 
Published: April 2011

ABSRACTHigh throughput screening methods for evaluating oxygen and moisture barriers are described. The screening methods are based on the change in a certain optical property, such as absorbance or fluorescence, due to a chemical reaction with oxygen gas or water vapor. The results of these measurements for several cases are presented and their advantages and disadvantages are discussed.
Synthesis and characterization of combinatorial libraries of semiconductor gas sensors.
Authors: Aronova M. A. , Chang K. S. , Takeuchi I. , Jabs H. , Westerheim D. , Gonzalez-Martin A. , Kim J. , Lewis B. 
Published: April 2011

ABSTRACTWe have fabricated thin-film combinatorial gas sensor libraries based on doped semiconducting SnO2 thin films. The utility of combinatorial libraries is two-fold: one is to search and optimize the compositions for high sensitivity and selectivity of gases, and the other is to make use of the natural array geometry of the libraries with different sensor elements for electronic noses. Combinatorial pulsed-laser ablation was used to deposit compositionally varying arrays of sensor elements onto a pre-patterned device electrode configuration. Using a multiplexing electronics, we have demonstrated detection of chloroform, formaldehyde, and benzene gases at concentrations down to 12.5 ppm through pattern recognition of signals from the arrays of sensors.
The study of luminescence of rare-earth organic complexes sensitized Eu3+ complex in PMMA matrix using combinatorial method
Authors: Ding Jianjun , Jiu Hongfang , Bao Jun , Lu Jiecheng , Gui Wanru , Zhang Qijing , Gao Chen 
Published: April 2011

ABSTRACTA combinatorial approach has been utilized for researching the luminescence of rare-earth ions complexes (RE(DBM)3·Phen, RE=Dy3+, La3+, Gd3+, Sm3+, Y3+) sensitized Eu3+ complex in PMMA matrix. The results show that the La3+ complex has the maximum sensitization efficiency among these sensitization ions. The luminescent intensities increase as the Eu content increase in PMMA matrix. The La3+ complex exhibits higher sensitization efficiency at lower Eu content in PMMA matrix. At a content of 5% Eu complex, the maximum sensitization efficiency of La3+ is more than 20 times.
Effects of Oxygen on Meta-stable Phase Formation in Zr80Pt20 Melt Spun Ribbons
Authors: Sordelet Daniel , Yang Xiaoyun , Rozhkova Elena , Besser Matthew , Kramer Matthew 
Published: April 2011

ABSTRACTThis report continues previous studies that show melt spun Zr80Pt20 ribbons having oxygen contents ranging from <200 to approximately 5000 mass ppm form various meta-stable phases during quenching. In the presence of sufficient oxygen, a big cube Zr6Pt3O phase forms, but this structure is de-stabilized towards an icosahedral quasicrystalline structure at lower oxygen levels. Further reduction of oxygen promotes increasingly stable Zr-Pt bonds, and a meta-stable β-Zr(Pt) structure is formed.
Crystal Chemistry and Electronic Structure of Magnesium based Mackay Icosahedron Type Approximants
Authors: Makongo Julien Pierre Amelie , Moguilnikov Yuri , Kudla Christian , Grüner Daniel , Schäpers Melanie , Kreinery Guido 
Published: April 2011

ABSTRACTIn order to obtain reliable experimental information on the long-range order, the role of the valence electron concentration and the type of disorder for Mackay icosahedron type quasicrystals we have studied binary and ternary Mg based approximant phases. An overview is presented on the crystal structures, homogeneity ranges, physical properties, and electronic structures of the following intermetallic phases: Mg6Pd, Mg57Pd13, Mg56.4Pd13.5, Mg306Pd77, Mg3Pd, Mg5Pd2, Mg2Pd, Ga30-xMg32+xPd21-y, Ga15-x-yMg38+yPd13+x, GaMg3Pd2, Ag17Mg54, Ag7Mg26, and AgMg4.
Chemical Bonding and Pseudogap in Zn- and Cd-based Compounds with Complex Hexagonal Structures
Authors: Ishii Y. , Nozawa K. , Fujiwara T. 
Published: April 2011

ABSTRACTElectronic structures of hexagonal Zn-Mg-Y and Cd58Y13 compounds are studied by first-principles calculations. Both of the systems show deep pseudogap in the electronic density of states near the Fermi level and considered to be stabilized electronically. To illustrate bonding nature of electronic wavefunctions, the crystal orbital Hamilton population (COHP) is calculated for neighboring pairs of atoms in the unit cell. It is found that the bonding nature is changed from bonding to anti-bonding almost exactly at the Fermi level for Zn-Zn and Cd-Cd bonds. On the contrary, for Zn/Cd-Y bonds, both of the states below and above the pseudogap behave as bonding ones. Possible effects of the p-d hybridization are discussed.
Stability and Icosahedral Transformation of Supercooled Liquid in Metal-Metal type Bulk Glassy Alloys
Authors: Inoue Akihisa , Zhnag Wei , Louzguine Dmitri V. , Saida Junji , Matsubara Eiichiro 
Published: April 2011

ABSTRACTThe glassy structure and the primary precipitation phase from supercooled liquid were examined in metal-metal type Zr-, Hf- and Cu-based alloy systems by various advanced analytical techniques. The icosahedral phase precipitates as the primary phase from supercooled liquid for all the metal-metal type glassy alloys examined in the present study. The icosahedral phase has a rhombic triacontahedra type for the Zr-Al-Ni-Cu-NM (NM=Ag, Pd, Au, Pt), Zr-Cu-NM, Hf-Al-Ni-Cu-NM, Cu-Zr-Ti-Pd and Cu-Hf-Ti alloys. In addition, the short-range atomic configurations in their glassy alloys have the features of highly dense packed atomic configuration, new local atomic configurations and long-range homogeneity with attractive interaction. It is therefore concluded that the high glass-forming ability of the metal-metal type alloys is due to the self-formation of the unique glassy structure with the above-described three features which are consistent with the formation of short-range icosahedral atomic configuration.
Structural Relationships between QC and Meta-stable Crystalline Phases in Melt Spun Zr80Pt20 Ribbons
Authors: Yang X. Y. , Kramer M. J. , Rozhkova E. A. , Sordelet D. J. 
Published: April 2011

ABSTRACTTwo competing meta-stable crystalline phases, a bcc hyperstoichiometric β-Zr(Pt) (Im3m) superstructure and a non-stoichiometric fcc ε-Zr6Pt3O (Fd3m) phase, have been observed to coexist with a quasicrystalline (i) phase, respectively, in as-spun Zr80Pt20 ribbons with low oxygen content (184ppm mass O) and high oxygen content (4737 ppm mass O). Transmission electron microscopy (TEM) results show that the β-Zr(Pt) superstructure and i phase have a well defined orientational relationship, good crystallographic match and nearly identical stoichiometry. Icosahedral two-fold axes coincide with <110>, <111>, <112> and <113> axes in β-Zr(Pt); {110}β-Zr planes register with icosahedral {211111} fivefold or {221001} twofold planes. The observed orientational relationship and the space group (Im3m) preclude β-Zr(Pt) as a cubic approximant to the i phase. Both β-Zr(Pt) and the i phase are distorted; β-Zr(Pt) maintains a basic β-Zr Bravais lattice with an aperiodic superlattice. Morphologies suggest that the i phase forms first, followed by an easy nucleation of the β-Zr(Pt) on the surfaces of the i phase. Also, a similar orientational relationship and lattice match between ε-Zr6Pt3O and i phase has been revealed by TEM.
Electrical Properties of Ag-In-(Yb,Ca) Quasicrystals and Their Approximants
Authors: Tetsuka Daisuke , Tamura Ryuji , Takeuchi Shin 
Published: April 2011

ABSTRACTWe report the electrical resistivity of the ternary Ag-In-(Yb,Ca) quasicrystals (QCs) together with those of their 1/1 and 2/1 cubic approximants. The temperature coefficient of the resistivity (TCR) is negative and nearly the same for the QCs and the 2/1 approximants suggesting that the coherence length of the conduction electrons in the QCs is comparable to the lattice parameter of the 2/1 approximants, i.e., ∼2.5 nm. On the other hand, both positive and negative values of TCR are observed for the 1/1 approximants depending on the annealing temperature. Taking into consideration the occurrence of positive TCR in the binary Cd-(Yb,Ca) 1/1 approximant, the latter phenomenon suggests that the negative TCR of the ternary 1/1 approximants is due to chemical disorder between Ag and In, and the chemical disorder is possibly reduced when annealed at low temperatures.
Wetting and friction on quasicrystals and related compounds
Authors: Dubois Jean Marie , Fournée Vincent , Belin-Ferré Esther 
Published: April 2011

ABSTRACTReduced wetting and friction are two essential surface properties that to a large extent currently embody the technological potential of quasicrystalline coatings. By quasicrystalline compounds, one considers here the whole family of complex Al-(Cu or Pd)-(Fe, Cr or Mn) intermetallics, which comprises true quasicrystals, their approximants and some crystalline materials of related composition.Although covered by a layer of native Al2O3oxide, wetting by water on these materials exhibits a clear correlation between the reversible adhesion energy of water and the bulk density of states at the Fermi energy. Similarly, in high vacuum, the friction coefficient measured in contact against a hard-steel rider is characteristically smaller than the one measured against conventional metallic alloys (including steel). Observing that wear is nearly non existent under such friction conditions, experiment allows us for the first time to derive a fair estimate of the true surface energy of quasicrystals and related complex metallic alloys. Similarly to wetting, the electronic density of states seems to determine the friction characteristics of these compounds.
Debye Temperature at the Fivefold- and Threefold-Symmetry Surface of the Al-Pd-Mn Quasicrystal.
Authors: Lüscher R. , Flückiger T. , Erbudak M. , Kortan A. R. 
Published: April 2011

ABSTRACTSpecular-beam intensity profiles are measured in low-energy electron diffraction as a function of temperature for the fivefold- and threefold-symmetry surfaces of the icosahedral quasicrystal Al-Pd-Mn. The resulting shifts of the Bragg-peaks to lower energies are accounted for mainly by a lattice expansion perpendicular to the surface and allow us to determine the thermal expansion coefficient of atomic layers to be (24.5 ± 2.0) × 10−6 K−1 for both surfaces. As a result of several measurements, a surface Debye temperature of 298 ± 7 K is found for the pentagonal and 301 ± 10 K for the threefold-symmetry surface. This similarity implies comparable bonding forces for the atoms at these surfaces. Additionally, the derived thermal expansion coefficient supports a layer-based structural model for both surfaces investigated here.
Electrochemical Reactivity of Zirconium-Based Bulk Metallic Glasses
Authors: Gebert Annett , Kamachi Mudali U. , Eckert Jürgen , Schultz Ludwig 
Published: April 2011

ABSTRACTAmorphous Zr-(Ti)-(Nb)-Al-Cu-Ni alloy samples were prepared by melt-spinning and copper mould casting in an argon atmosphere and characterized regarding their microstructure and thermal behavior. Their anodization behavior in aqueous environments with pH= 0.5 – 13 was studied by electrochemical polarization techniques in combination with surface analytical investigations, i.e. SEM/EDX, AES. In chloride-containing solutions the macroscopic corrosion resistance of bulk amorphous alloys is affected by the presence of heterogeneities, such as concentrated cluster zones of selected components or crystalline defects. Pitting phenomena are studied in neutral and acidic chloride solutions and as a result a local corrosion mechanism is proposed. The cathodic reactivity of alloy samples at different microstructural states and after pre-etching in fluoride solutions was investigated. After pre-etching melt-spun amorphous samples exhibit a significant increase in surface reactivity as expressed by a drastic increase in electrochemical capacities and in cathodic current densities as well as by a significant reduction of overpotentials for the hydrogen reduction reaction. The hydrogen sorption behavior was studied on samples galvanostatically charged at various cathodic current densities by means of XRD, DSC, TEM and thermal desorption analysis TDA. At room temperature Zr-based alloys absorb hydrogen up to H/M=1.65 mainly by interstitial solution of hydrogen atoms in the amorphous structure. The effect of absorbed hydrogen on the thermal stability and the crystallization behavior is described.
Bulk metallic glasses for industrial products; New structural and functional applications
Authors: Nishiyama Nobuyuki , Amiya Kenji , Inoue Akihisa 
Published: April 2011

ABSTRACTBy use of excellent properties of bulk metallic glasses, some industrial products were practically prepared and their performances were investigated. Linear actuator constructed by a set of Fe-based BMG yokes generates large Lorentz force due to the large permeability and saturation magnetization of the BMG. Ni-based BMG microgear prepared by injection casting exhibits nano-imprintability against the surface roughness of mold. The newly developed alloy with a nominal atomic composition of Ti52Cu23Ni11Mo7Fe7 exhibits high yield strength of 1250 MPa, high fracture strength of 2740 MPa and large plastic elongation of over 20 %. These results for the industrial products made of BMGs are promising for future developments as industrial materials with high performance.
Increased, Directed Osteoblast Adhesion at Nanophase Ti and Ti6Al4V Particle Boundaries
Authors: Webster Thomas J. , Ejiofor Jeremiah U. 
Published: April 2011

ABSTRACTIncreased functions of osteoblasts (bone-forming cells) have been demonstrated on nanophase compared to conventional ceramics (specifically, alumina, titania, and hydroxyapatite), polymers (such as poly-lactic-glycolic acid and polyurethane), carbon nanofibers, and composites thereof. Nanophase materials are materials that simulate dimensions of constituent components of bone since they possess particle or grain sizes less than 100 nm. However, to date, interactions of osteoblasts on nanophase compared to conventional metals remain to be elucidated. For this reason, the objective of the present in vitro study was to design, fabricate, and evaluate osteoblast adhesion on nanophase metals (specifically, Ti and Ti6Al4V). Results of this study provided the first evidence of increased osteoblast adhesion on nanophase compared to conventional Ti-based metals. Moreover, directed osteoblast adhesion was observed preferentially at metal particle boundaries. It is speculated that since more particle boundaries were created through the use of nanophase compared to conventional metals, increased osteoblast adhesion resulted. Because adhesion is a necessary prerequisite for subsequent functions of osteoblasts (such as deposition of calcium-containing mineral), the present study suggests that Ti-based nanophase metals should be further considered for orthopedic implant applications.