Materials Literature
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Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of $\mathrm{La}{}_{5/3}\mathrm{Sr}{}_{1/3}\mathrm{NiO}{}_{4}$ at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge…
A quantitative analysis of the surface composition of the Heusler alloy NiMnSb has been undertaken using angle-resolved x-ray photoemission spectroscopy and the surface composition characterized. With sufficient annealing cycles, the stoichiometric surface evolves to a surface that is manganese rich. This indicates th…
We present a complete experimental determination of the atomic parameters necessary to unambiguously characterize two-photon ionization of atomic rubidium, i.e., the relative photoionization cross sections and the continuum wave function phase difference. We obtain these complete results through a single measurement,…
Atomic force microscopy tips are used to apply point-like local gates to manipulate the electrical properties of individual single-walled carbon nanotubes (SWNT) contacted by Ti electrodes. Depleting a semiconducting SWNT at a local point along its length leads to orders of magnitude decrease of the nanotube conductan…
Large luminescence enhancement was observed in EuS clusters formed in ultrastable zeolite-Y by solid-state diffusion in vacuum at 600 °C. The emission of EuS clusters shifts to higher energies relative to that of bulk EuS powder. The blueshift and the emission enhancement are attributed to quantum-size confinement and…
Nonlinearity is observed in Fowler–Nordheim (FN) plots of field emission from nondoped and nitrogen-doped amorphous diamond films. Based on a unified electron emission equation a detailed analysis is carried out. The results from numerical calculation of the unified equation are consistent with the experimental data.…
Field emission data from aligned high-density carbon nanotubes (CNTs) with orientations parallel, 45°, and perpendicular to the substrate have been obtained. The large-area uniformly distributed CNTs were synthesized on smooth nickel substrates via dc plasma-assisted hot filament chemical vapor deposition. CNTs with d…
The dynamic structure factors S(q-->,omega) of diamond and LiF have been measured using inelastic x-ray scattering. The experimental data are compared to results of ab initio calculations, which take into account the interaction of the excited electron with the remaining hole. In diamond, the vicinity of the indirect…
We show that the anchoring memory of liquid crystals on solid substrates can be completely removed by grafting highly mobile polymer chains. Using grafted polystyrene, we obtain uniform, stable, and reproducible memory-free and conically degenerated anchoring of the nematic 5CB. The symmetry of the conic anchoring ena…
We have mapped the growth mode of homoepitaxial SrTiO3 thin films as a function of deposition rate and substrate temperature during pulsed laser deposition. The transition from layer by layer growth to step flow growth was mapped by making 260 depositions, 3 monolayers each, on a single substrate. The growth mode was…
High pressure Raman spectroscopic studies are carried out on negative thermal expansion material ZrW2O8. The system exhibits amorphization at 2.2+/-0.3 GPa via an intermediate orthorhombic phase. In the cubic phase most modes below 50 meV are found to have negative Gruneisen parameter. Using the reported phonon densit…
The dielectric properties of (Ba, Sr)TiO3 films were found to be remarkably sensitive to the postannealing treatment atmosphere. This study demonstrates that postannealing in an oxygen atmosphere increases the dielectric relaxation phenomenon and that postannealing in a nitrogen atmosphere produces a slight dielectric…
We present extensive modeling of the amorphous silica surface, aimed at connecting its structural and chemical features. beta-cristobalite surfaces are initially studied to model the hydroxylated surfaces. A model reconstruction of the (111) surface is used to define a path leading to the formation of two-membered sil…
Bi 2 Sr 2 Co 2 O 9 (BC-2202) polycrystalline materials with a layered structure have been prepared by partial melting. The chemical compositions of the samples are Bi2Sr2Co2Ox (2202), Bi1.8Sr2Co2Ox (Bi-1.8), and Bi2Sr1.8Co2Ox (Sr-1.8). All three samples are p-type conductors. The electric properties, namely, the Seebe…
Vertically aligned carbon nanotubes were synthesized on Ni-deposited Si substrates using microwave plasma-enhanced chemical vapor deposition. The grain size of Ni thin films varied with the rf power density during the rf magnetron sputtering process. We found that the diameter, growth rate, and density of carbon nanot…
Silicon nanocrystals were formed in SiO2 using Si ion implantation followed by thermal annealing. The nanocrystal-doped SiO2 layer was implanted with Er to a peak concentration of 1.8 at. %. Upon 458 nm excitation the sample shows a broad nanocrystal-related luminescence spectrum centered around 750 nm and two sharp E…
Effects of lattice strain on magnetic behavior of epitaxial La0.67Sr0.33MnO3 thin films grown by 90° off-axis sputtering have been studied. The size of epitaxial strain was varied using four different substrates, i.e., (001) LaAlO3, (001) SrTiO3, (001) La0.3Sr0.7Al0.65Ta0.35O9, and (110) NdGaO3. The observed magnetism…
The mechanisms of the adsorption of stereoregular polymers are only poorly understood. This work is devoted to the study of the influence of PMMA tacticity and conformation on the interfacial behavior of the polymer. 1 H NMR usually used to determine the tacticity of PMMA in solution in CDCl 3 can also be applied to s…
The effects of N - and C -methyl substitution on electrical and spectral properties of pyrrole, 2,2‘-bipyrrole, and the corresponding polymers were investigated. The whole series of monomethyl and N - or C β -dimethyl-substituted 2,2‘-bipyrroles was synthesized, and the electrochemical and spectral properties of all t…
The structure of ionic aggregates in commercially important ethylene ionomers was studied by small-angle X-ray scattering (SAXS). The samples examined were sodium and zinc salts of poly(ethylene- co -13.3 mol % methacrylic acid) (EMAA) ionomers, which were found to be noncrystalline unlike commercially available EMAA…