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QUANTUM MODELING FOR HIGH-ENTROPY ALLOYS Materials researchers at the DOE's Ames Laboratory, Iowa, recently identified the source of strength and ductility in high-entropy alloys (HEAs), along with ways to tune [...]

BACKGROUND: There has been concern regarding risks from inhalation exposure to nanoparticles (NPs). The large number of particles requiring testing means that alternative approaches to animal testing are needed. OBJECTIVES: [...]

The realization of high-transition-temperature (high-[T.sub.c]) superconductivity confined to nanometre-sized interfaces has been a long-standing goal because of potential applications (1, 2) and the opportunity to study quantum phenomena in reduced [...]

The studies about the neutral and anionic molecules of the monomers and dimers of the group of transition metal oxides (M[O.sub.3] and [M.sub.2][O.sub.6] where (M = Cr, Mo, and W) is reported. Result showed that BP86 functional yielded best overall results for the vertical electron detachment energies (VDEs) of all the metal oxide clusters studied.

The aim of this work is to study the effect of metallic oxides additions to mortars on their mechanical and long-term environmental behaviors. Four common metal oxides were selected ([Fe.sub.2][O.sub.3], [Zn.sub.O], as main oxides and a mix of PbO+[Cr.sub.2][O.sub.3], as minor oxides) and incorporated in mortars using a fractional factorial design ([2.sup.3-1] + 3) of experiments. The studied variables were: setting time (ST), compressive and flexural strengths (UCS and UFS), availability, effective diffusion coefficient (De), and immission after 100 years. The analysis of the results shows that ZnO and [Fe.sub.2][O.sub.3] are statistically significant on the mechanical properties at short ages. ZnO increases the ST and it decreases the UCS and UFS, whereas [Fe.sub.2][O.sub.3] shows an antagonistic effect. The metal release from monoliths was low, leading to small values of De. Finally the estimated immission of Pb, Zn, and Cr after 100 years were lower than the standard limit of Dutch regulation. CE Database subject headings: Mortars; Heavy metals; Mechanical properties; Environmental impacts.

The self-assembly of organosilicon hydrides on the surface of hydrated metal oxides is catalyzed by the water adsorbed onto the acid and basic sites (Lewis and Bronsted) of the metal oxide. This method can be used for selective modification of chemically heterogenous surfaces, nano-patterning, and other applications.

A new strategy is introduced wherein small complexes are combined with linear metal cations to produce metal oxide nanowires. The copper oxide monocrytalline nanowires are made through the complex precursor surfactant assisted route.

An efficient hydrogen evolution was achieved on layered metal oxides incorporating CdS in interlayer, which were prepared by direct cation exachange reaction and a sulfurization process. It was observed that photocatalytic hydrogen production under visible light was confirmed by the fact that H2 was detected when UV light was removed.

We report experimental evidence for a full orbital ordering transition in the two-dimensional lanthanum ruthenate [La.sub.4][Ru.sub.2][O.sub.10]. The observable consequences of this orbital ordering include the loss of the Ru local moment, a structural distortion which partitions Ru-O bonds into axially oriented short and long sets, a sharp jump in electrical resistivity, and the opening of a spin gap that is visible in neutron scattering experiments. This is a rare example of a discrete orbital ordering transition in a 4d transition metal oxide and demonstrates that orbital effects can have an influence on the properties of layered ruthenates, a family of compounds that notably includes the p-wave superconductor [Sr.sub.2][Ru.sub.2][O.sub.4] and the field-tuned quantum critical metamagnet [Sr.sub.3][Ru.sub.2][O.sub.7]., The study of the interplay between orbital, spin, and charge degrees of freedom in transition metal oxides is at the forefront of condensed-matter physics (1). Invariably, the canonical examples of [...]

Plasam-neutral gas structures are examined in detail. A model is developed with a number of elements and is compared with the results of an experiment.

The molecular structures of supported metal oxide species are studied using Ultraviolet (UV) and visible Raman spectroscopy. The study concluded that the large body of Raman spectra from catalysts measured using visible lasers should be very useful for interpreting new measurements using ultraviolet lasers.

The study shows that vibrational spectroscopy may be a valuable tool to study ultrasmall metal particles and single metal atoms. It is concluded that infrared spectroscopy might contribute to the elucidation of structure and charge of ultrasmall supported metal aggregates with sizes down to a single atom.

Spark plasma sintered Ca2.75Gd0.25Co4O9 ceramics were studied to determine their thermoelectric properties.

An investigation of the effects of temperature on the intensities and positions of Raman bands of bulk and supported metal oxides is presented. The results show that bulk oxides exhibit an increase in optical absorption with increasing temperature due to a loss of oxygen and the consequent formation of nonstoichiometric oxides and stoichiometric suboxides.

Strontium ruthenate, a metal oxide, and its superconductivity is examined.

The syntheses, structures and dynamics of wheeling templates in molecular oxothiomolybdate rings are examined.

Research is presented concerning the production of perovskite oxides, via a metathesis reaction with MCl2, BiOCl and VOSO4.3H20, from a transformation of the Ruddlesden-Popper oxide K2La2Ti3O10.

The preparation is described of Ba2Co2Fe28O46 nanocrystals using a stearic acid sol-gel method.

A report is presented of the preparation of Ag2O nanocrystals using a chemical method.

Issues concerning the synthesis by topochemical means of three-dimensional perovskites from lamellar Dion-Jacobson and Ruddlesden-Popper starting materials are presented. Oxygen loss accompanying the reduction of one of the ions is used to form the perovskites which keep the anisotropic texture of their layered starting materials.

An investigation into the interaction of CF3CfCl2 with gamma-Al2O3 uses a combination of FTIR spectroscopic research and reaction kinetics experiments. Details of the study are discussed.

A new study uses a matrix isolation method to investigate the reaction of OVCl3 with CH3OH, followed by trapping to argon matrices.

An investigation of the alkaline earth metal atom reactions with NO2 is presented. The compounds selected for test are Mg(1S), Ca(1S), and Sr(1S). Temperature ranges are 303-836 K, 303-916 K and 303-986 K.

Research into the role electrolyte anions play in metal adsorption from oxide and hydroxide surfaces in salt solutions is presented. Similar results to previous studies were obtained using the extended triple-layer model, but contrasting results were found with solids such as goethite, corundum, and anatase.

Research demonstrates that stable metal complexes incorporating metals in oxidation states can be prepared by (R(sub)3tach)M(C0)(sub)3 oxidation. Data show that the complexes can be crystallized into 3-axes of rhombohedral shape.

Research was conducted to examine the effect of laser ablated plume size for deposition of aluminum films in oxygen and nitrogen ambient atmosphere. Imaging was used as a tool to optimize the laser ablated plume parameters with respect to laser parameters and target-substrate distance for growth and characterization of metal nitride films at room temperature. Results show that the formation of aluminum nitride is caused by the breakdown of nitrogen gas due to high shock temperature and subsequent mixing with aluminum plasma in the shocked region.

The photoelectrochemical technique was used to study the deposition of metallic oxides onto both single crystal and polycrystalline TiO2 electrodes wherein the electrochemical behavior of the prepared PbO2/TiO2 electrode was also studied. Under illumination, the photoelectrodeposition of PbO2, Fe2O3 and MnO2 occured but not in the dark. Strong dependence on the crystal misfit between the TiO2 substrate and the oxides influenced the crystal orientation of the deposited oxides.

A study relating to research on metal oxides investigated laser-ablated yttrium and lanthanum atom reactions with O2 that were compared to the analogue scandium reactions. Laser-ablated yttrium and lanthanum condensed with O2 in excess argon formed the metal oxides, cations and anions that were identified from isotopic substitution and density functional calculations. Experimental methods, findings and conclusions are presented.

A study was conducted to investigate the bulk and surface reduction of hydrogen of mixed ceria-zirconia mixed oxides. Using Fourier transform infrared spectroscopy and magnetic susceptibility measures, it was found that the integration of the zirconium ions in the ceria lattice decreases the number of cerium ions by facilitating surface reduction and raising the oxygen mobility in the bulk.

A study was conducted to characterize the structure of a mixed electron-proton conductor with specific capacitance called hydrous ruthenium oxide. Analysis of data gathered from thermogravimetric analysis, X-ray diffraction and X-ray absorption spectroscopy revealed that the local structures of the hydrous ruthenium oxides affect their electrochemical properties, particularly those that allow them to store energy.

A study on the use of ferroelectric thin films as key materials for non-volatile random access memory devices presents the first experimental results concerning structural changes caused by H2 annealing in a Pb(Ze,Ti)O3 film fabricated on a Pt electrode. The experiment describes the outline of electron energy loss spectroscopy calculations and discusses the computational results. Findings indicate that the Pb(Zr,Ti)O3 crystal structure was deformed in the interfacial area with the Pt electrode during H2 annealing. The deformation altered the Ti-O orbital overlaps.

A study was conducted on the use of the ferroelectric material LiNbO3 for optoelectronic and surface-acoustic-wave (SAW) devices. The experiment attempted to collect basic data on the acoustic properties of leaky-surface-acoustic-wave velocities that are related directly to chemical compositions prior to applying line-focus-beam acoustic microscopy to characterize MgO-doped LiNbO3 crystals and wafers. Experimental results are presented.

A study was conducted on the use of chemie douce techniques to synthesize highly homogeneous and sometime microporous materials. The experiment focused on the synthesis of cadmium oxide from a hydroxyl gel. Combinations of x-ray diffraction, x-ray absorption fine structure spectroscopy and small angle x-ray scattering afford a comprehensive in situ view of the development of the crystallography, local atomic structure and microstructure of the synthesized cadmium oxide.

The isolation of the dimeric complexes (ATi(Oneo-Pe)5)2 (A=Li), Na and K, independent of the alkali metal investigated, was the result of the reactions of titanium(IV) neopentoxide, (Ti(mu-Oneo-Pe)(Oneo-Pe)3)2 with alkali neopentoxides (AOneo-Pe). Solution and solid-state multinuclear NMR, isopiestic molecular weight determination, and single-crystal X-ray diffraction characterized each compound. In the solid state, both Li and K were found to adopt a standard (MM'(OR)5)2 arrangement, wherein the Ti metals were in a distorted trigonal-bipyramidal geometry.

Extended Huckel molecular orbital calculations were carried out in studying the spin-spin interactions in the oxides A3M'MO6 where M = Rh, Ir; A = Ca, Sr; M' = alkaline earth, Zn, Cd, Na of the K4CdCl6 structure type. Results indicate that the spin-spin interactions in these oxides are three-dimensional and the superexchange interactions proceed through the short intrachain and interchain M-O***O-M linkages. The intrachain interaction is stronger than the interchain interaction when the M(super n+) cation is smaller than the A(super 2+) cation.

The reactivity of alumina under gamma irradiation has been investigated by focusing on radiation-induced catalysis on metal oxide surfaces. The objective is to determine if charge separation and charge transfer leads to catalytic degradation of an adsorbed compound, hexachlorobenzene. Radiolytic transformation of hexachlorobenzene adsorbed to alumina and potassium bromide was analyzed using different techniques, including diffuse reflectance, ultraviolet and Fourier transform infrared spectroscopy. Results show that hexachlorobenzene conversion to dechlorinated products decreases as surface coverage on alumina increases, suggesting the crucial catalytic role of the support material.

Thiolactate-modified 45 Angstrom TiO(sub 2) particles self-assemble into rodlike structures. The rod formation was observed using the small-angle neutron scattering technique, with the rod diameter calculated at 43.2 plus or minus 1.6 Angstrom. The diameter of the rods was found to be the same for both self-organized and unassembled TiO(sub 2) nanoclusters and was independent of TiO(sub 2) concentration or pH. On the other hand, rod length was sensitive to both TiO(sub 2) concentration and pH.

The isomorphic substitution and postsynthesis introduction of zirconium metal centers into the cubic phase of mesoporous silica are described. The process involves hydrothermal Si/Zr coprecipitation and postsynthesis functionalization of surface silanols with zirconium propoxide. Results from nitrogen sorption and X-ray powder diffraction experiments show that the structure, high surface area and narrow pore size distribution are maintained. Grafting with zirconium propoxide yields the most isolated metal species.

A study was conducted on metallic behavior-exhibiting conducting oxides such as La1-xSrxCoO3 as promising electrode material for solid oxide fuel cells or non-volatile ferroelectric memories. The experiment will demonstrate that the reverse effect, or a decrease of the optical absorption coefficient value, during laser irradiation between roughly the same values as those mentioned in previous experiments, are most likely responsible for the occurrence of splashing after extended time periods of laser ablation of the same La1-xSrxCoO3 target.

A study was conducted to investigate the structural evolution of Bi2CuO4 during the ball milling process to explore the ability of mechanical deformation in inducing phase transformation for this oxide. It will be shown that the complete amorphization of Bi2CuO4 can be realized, though it is not an easy glass former, by quenching the molten liquid. Further, a new phase is induced by the mechanical deformation. Experimental methodology and findings are presented.

A study was conducted to understand the basic mechanisms and identify the parameters linked to the dynamic annealing of ion-beam induced damage in alpha-quartz at elevated temperatures. The experiment aims to further the understanding of ion-beam-induced epitaxial growth in the recrystallization process. Among other experimental results, it was found that the critical temperature above which no amorphization takes place is roughly 940 K.

A study was conducted to analyze hydrogen adsorption on the V2O5(010) surface using density functional computations. Results indicated that the use of a periodic approach eliminates artifacts of the cluster technique. In addition, findings confirmed the effectiveness of using the density functional theory in examining the geometric, electronic and catalytic characteristics of transition metal oxide catalysts.

The polar (WO(sub 2)F(sub 4))(super 2-) anion is crystallized with two different cations in the solid state to order one of the two W=O bonds. Close examination of bond lengths and anisotropic thermal ellipsoids in disordered (WO(sub 2)F(sub 4))(super 2-) compounds elucidates the disorder mechanisms and suggests strategies for eliminating orientational disorder. The anion is inherently acentric and consists of polarizable W=O bonds.

A study was conducted to analyze the equilibrium geometries, binding energies, electronic structure and magnetic characteristics of small stoichiometric MnO clusters. The analysis was based on self-consistent computations carried out with the density functional theory and the generalized gradient approximation. Differences were found in the structural growth of the clusters. In addition, the magnetic characteristics of the clusters support unique properties.

A study was conducted to analyze the characteristics of carbon dioxide activation at metal centers in the gas phase. The reactions of Y+ and YO+ with CO2 and the reverse reactions of YO+ and YO2+ with CO2 were also examined. Ion beam mass spectrometry was utilized to carry out the analysis. Experimental results indicated that yttrium cations reacted with carbon dioxide to form two ionic products.