Materials Literature
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This article presents an analytical and experimental study of magnetohydrodynamic Rayleigh–Bénard convection in a large aspect ratio, 20[ratio ]10[ratio ]1, rectangular box. The test fluid is a eutectic sodium potassium Na 22 K 78 alloy with a small Prandtl number of Pr≈0:02. The experimental setup covers Rayleigh num…
Thin, Pd-capped metallic films containing magnesium and first-row transition metals (Mn, Fe, Co) switch reversibly from their initial reflecting state to visually transparent states when exposed to gaseous hydrogen or following cathodic polarization in an alkaline electrolyte. Reversion to the reflecting state is achi…
Switching of the out-of-plane and in-plane polarizations in polydomain epitaxial PbZr0.2Ti0.8O3 thin films is studied using three-dimensional piezoresponse force microscopy (PFM). It is found that, under an electric field induced between the PFM tip and the bottom electrode, the 180° switching occurs in both c and a d…
We present an experimental and theoretical description of the kinetics of coalescence of two water drops on a plane solid surface. The case of partial wetting is considered. The drops are in an atmosphere of nitrogen saturated with water where they grow by condensation and eventually touch each other and coalesce. A n…
Composite structures of single walled carbon nanotubes (SWNTs) and poly(3-octylthiophene) polymer were tested as field emitters. The structures studied were formed on n+-Si by mixing the two materials after they had been dissolved in chloroform. Three different structures were tested: (a) a SWNT mat, (b) a SWNT mat on…
In order to improve the color purity of YBO3:Eu, which is practically used as a plasma phosphor, the lowering of the structural symmetry is proposed and subsequently realized in nanosized YBO3:Eu so as to increase the contribution of D05–F27 transition of the luminescent centers, Eu3+ ions. Spherical YBO3:Eu nanocryst…
The magnetic properties of perovskite CaVO3 single crystals have been studied by means of magnetoresistance r(T, H) and magnetization M(H) measurements in fields to 18T. At 2 K, the magnetoresistance is positive and a maximum value of Dr(18T)/r(0) = 16.5% is found for H//a. The magnetization exhibits a smooth increase…
Crystalline structures, zone-center phonon modes, and the related dielectric response of the three low-pressure phases of HfO2 have been investigated in density-functional theory using ultrasoft pseudopotentials and a plane-wave basis. The structures of low-pressure HfO2 polymorphs are carefully studied with both the…
A simple (2+1) dimensional discrete model is introduced to study the evolution of solid surface morphologies during ion-beam sputtering. The model is based on the same assumptions about the erosion process as the existing analytic theories. Due to its simple structure, simulations of the model can be performed on time…
Gold Schottky-barrier diodes (SBDs) were fabricated on vapor-phase-grown single-crystal ZnO. Deep-level transient spectroscopy, using these SBDs, revealed the presence of four electron traps, the major two having levels at 0.12 eV and 0.57 below the conduction band. Comparison with temperature-dependent Hall measureme…
We give a physical picture of the low-energy sector of the spin 1/2 Heisenberg Kagome antiferromagnet (KAF). It is shown that Kagome lattice can be presented as a set of stars which are arranged in a triangular lattice and contain 12 spins. Each of these stars has two degenerate singlet ground states which can be cons…
Nitrogen acceptors are formed when undoped single crystals of zinc oxide (ZnO) grown by the chemical-vapor transport method are annealed in air or nitrogen atmosphere at temperatures between 600 and 900 °C. After an anneal, an induced near-edge absorption band causes the crystals to appear yellow. Also, the concentrat…
We demonstrate that angle-resolved soft x-ray spectroscopy can resolve absorption by inequivalent oxygen sites and by different orbitals belonging to the same site in NaV2O5. By rotating the polarization direction, we see a dramatic change in the absorption spectra at the oxygen K edge. Our theory identifies the detai…
We have developed a simple and reliable technique for two-terminal transport measurements of free-standing wire-like objects. The method is based on the low-energy electron point source microscope. The field emission tip of the microscope is used as a movable electrode to make a well-defined local electrical contact o…
[structure: see text] The synthesis, theoretical calculations, and crystallographic and electrochemical properties of fused perpendicular tetrathiafulvalene (TTF) dimers incorporating both a TTF unit and a quinonoid pi-extended TTF are described as a new strategy for obtaining pi-extended, rigidified, and sulfur-rich…
In this paper, we describe a novel approach for fabricating an optoelectrochemical microring array. The array was fabricated by coating individual optical fibers of 25-microm diameter with a 1-microm layer of gold nanoparticles via electroless gold deposition. A SAM layer around the individual gold-coated imaging fibe…
Uncharged rods and disks have long been known to exhibit an isotropic to nematic phase transition on increasing density. In aqueous solution, however, such particles are generally highly charged, leading to repulsive electrostatic interactions. In this article the effect of adding salt to a monodisperse solution of th…
Carboxymethyldextrans of different charge densities have been attached to flat silicon wafer surfaces using plasma polymer interlayers in conjunction with two different chemical grafting strategies. The resultant coatings have been analyzed by XPS, to verify the surface coverage of the coatings and to estimate their d…
We report on the "molecular wiring" efficiency of glucose oxidase in organized self-assembled nanostructures comprised of enzyme layers alternating with layers of an osmium-derivatized poly(allylamine) cationic polyelectrolyte, acting as redox relays. Varying the relative position of the active enzyme layer in nanostr…
We describe our efforts toward the preparation of materials built with molecules possessing topologies analogous to those of macroscopic compasses and gyroscopes. Samples of 1,4-bis(3,3,3-triphenylpropynyl)benzene (3) were prepared by a simple two-step procedure from triphenylmethyl chloride (1) and 1,4-diiodobenzene.…