Materials Literature
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Ag(CN) 2 - is reduced at a low rate by radiolytically generated hydroxymethyl radicals. The reduction occurs on tiny nuclei in solution formed by hydrolysis. When colloidal silver seed particles are present in the solution, the reduction of Ag(CN) 2 - is much faster, and larger silver particles with a narrow size dist…
Abstract Ultraviolet (UV) weathering performance of unpigmented and rutile titanium dioxide pigmented rigid polyvinyl chloride (PVC)/wood‐fiber composites has been studied. The composite samples were manufactured by dry‐blending PVC, wood fibers, and other processing additives in a high‐intensity mixer. The dry‐blende…
A generic finite-element based approach for predicting the behavior and properties of multiphase materials comprised of anisotropic, arbitrarily shaped and oriented phases is presented. The approach is exact in principle and effective in practice. It is the consistent use of periodic boundary conditions in the course…
The effect of low magnetic fields on the transport properties of a manganite compound with magnetic phase separation is studied. The different behavior obtained in samples of ${\mathrm{La}}_{0.5}{\mathrm{Ca}}_{0.5}{\mathrm{MnO}}_{3}$ related to the way in which the low field is applied is consistent with a picture of…
We present the results of measurements of the thermal conductivity of the quasi one-dimensional spin S=1/2 chain compound SrCuO_2 in the temperature range between 0.4 and 300 K along the directions parallel and perpendicular to the chains. An anomalously enhanced thermal conductivity is observed along the chains. The…
Novel abrasion-resistant nanocomposites based on poly(methyl methacrylate) (PMMA) as matrix and calcium carbonate (CaCO 3 ) nanopowder as filler have been prepared by an in situ polymerization process. The influence of nanopowders on the chemical−physical properties of the polymeric matrix have been investigated by pe…
Antiferroelectric materials are found to be good alternative material compositions for high-charge-storage devices and transducer applications. Lead zirconate (PZ) is a room-temperature antiferroelectric material. The antiferroelectric nature of PZ thin films was studied over a temperature range of 24–300 °C, in terms…
We have measured the hydrogen depth profiles in chemical-vapor-deposited diamond films by elastic recoil detection. Depth resolution of ∼0.23 nm is achieved using a high-resolution magnetic spectrometer. The hydrogen depth profile shows a sharp peak at surface, and the hydrogen coverage is estimated to be 1±0.3 ML, in…
We report on the thickness d dependences of the Seebeck coefficient, electrical conductivity, and Hall coefficient of PbTe and PbS epitaxial thin films (d=5–200 nm), prepared by thermal evaporation in vacuum and deposition on (001) KCl substrates. The oxidation of the films in air at 300 K leads to a sign inversion of…
We report that single-bubble sonoluminescence (SBSL) at low light intensities produces emission bands similar to multibubble sonoluminescence (MBSL) for pure noble gas bubbles. A smooth crossover between SBSL and MBSL behavior can be induced by varying the acoustic pressure amplitude and thereby the intensity of the l…
Raman spectroscopy was used to map the stress distribution in the vicinity of discontinuities in a polymer using single-wall nanotubes seeded in the specimen. In the case of a hole in a polymer matrix subjected to unidirectional stress, the experimental stress field compared well with the classical linear elasticity s…
Thin-film capacitors, with barium strontium titanate (BST) dielectric layers between 7.5 and 950 nm in thickness, were fabricated by pulsed-laser deposition. Both crystallography and cation chemistry were consistent with successful growth of the BST perovskite. At room temperature, all capacitors displayed frequency d…
We report improvements in the crystallinity of a III–V-based diluted magnetic semiconductor (Ga, Mn)As by heat treatment (annealing) after growth at comparatively low temperatures. This method can be used to raise the Curie temperature to 100 K without the need for severe optimization of growth conditions, as well as…
The diffusive coarsening of 2D soap froths is governed by von Neumann's law. A statistical version of this law for dry 3D foams has long been conjectured. A new derivation, based on a theorem by Minkowski, yields an explicit analytical von Neumann's law in 3D which is in very good agreement with detailed simulations a…
We have studied the electronic structure of the skutterudite compounds Co(Sb$_{1-x}$Te$_{x}$)$_3$ (x= 0, 0.02, 0.04) by photoemission spectroscopy. Valence-band spectra revealed that Sb 5p states are dominant near the Fermi level and are hybridized with Co 3d states just below it. The spectra of {\it p}-type CoSb$_3$…
Low-temperature (1.8 K) excitonic absorption, reflection and photoluminescence spectra of mixed $Zn(P_{1 - x}As_{x})_{2}$ crystals were studied at $x = $0.01, 0.02, 0.03 and 0.05. Energy gap and rydbergs of excitonic B, C and A-series decrease monotonically at the increase of $x$. Spectral half-widths of absorption $n…
Sintered powders and wires of superconducting $MgB_2$ have been fabricated under a variety of conditions in order to determine details of the diffusion of the $Mg$ into $B$ and to study the types of defects that arise during growth. For samples prepared by exposure of boron to $Mg$ vapor at $950^{\circ}C$, the convers…
We investigate electronic structures of Al quantum wires, both unsupported and supported on the (100) NaCl surface, using the density-functional theory. We confirm that unsupported nanowires, constrained to be linear, show magnetization when elongated beyond the equilibrium length. Allowing ions to relax, the wires de…
Localized interface states in abrupt semiconductor heterojunctions are studied within a tight-binding model. The intention is to provide a microscopic foundation for the results of similar studies which were based upon the two-band model within the envelope function approximation. In a two-dimensional description, the…
The first global simulation of semiconductor-based quantum-cascade lasers is presented; Our fully three-dimensional approach allows to study in a purely microscopic way -without resorting to phenomenological parameters- the current-voltage characteristics of state-of-the-art unipolar nanostructures. Based on the propo…