Materials Literature
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The results of an investigation of the transient mid-gap photoluminescence (PL) and photo-induced optical absorption in trigonal Se are presented. Direct evidence is found for a barrier of 35\ifmmode\pm\else\textpm\fi{}5 meV to trapping of free excitons at the PL center. All the features of the PL, including the high-…
The optical-absorption coefficient \ensuremath{\alpha}(\ensuremath{\omega}) in heavily doped n- and p-type GaAs is evaluated for comparison with the observed values of Casey et al. The purpose is to test the theory of electrons in heavily disordered systems derived by Sa-yakanit and the absorption matrix element (ME)…
The electronic structures of lithium metasilicate (${\mathrm{Li}}_{2}$${\mathrm{SiO}}_{3}$) and lithium disilicate (${\mathrm{Li}}_{2}$${\mathrm{Si}}_{2}$${\mathrm{O}}_{5}$) are calculated using a first-principles orthogonalized linear combination of atomic-orbitals method. Results are compared with experimental x-ray…
The 5D3–5D4 cross relaxation process of Tb3+ in CsCdBr3 has been evaluated by analysis of the decay curves of the 5D3 and 5D4 emission. The temperature dependence of the cross relaxation rate can be explained assuming phonon-assisted processes. The results show that the larger amount of Tb3+ ions is incorporated in pa…
In order to study the temperature and stress dependence of Young’s modulus in semiconducting barium titanate ceramics, the longitudinal sound velocity was measured at a frequency of 5 MHz in the temperature range of 20–180 °C. It is striking that at temperatures above the Curie point (Tc=120 °C) the sound velocity rea…
An exact solution of the random-phase-approximation equations is worked out for the density-density correlation function of a semi-infinite system of two-dimensional electron-gas layers, with different dielectrics outside and inside the layered system. From this solution, analytic formulas are derived for the dispersi…
Small multiprobe resistors have been fabricated from continuous metal films of Ag, Al, Au, Cr, Cu, Mo, Nb, Ni, Pt, and W deposited under various conditions. Each shows some reproducible level of flicker (1/f) noise. This study implicates carrier scattering by extrinsic defects or impurities as the source of the resist…
Momentum-resolved inverse photoemission spectra from Ni(001), Ni(110), and Ni(111) have been measured. The results are presented in terms of final-state dispersions E(k${\ensuremath{\rightarrow}}_{\ensuremath{\parallel}}$) and compared to theoretical predictions on the basis of the bulk direct-transition model. Good a…
Thin films have been prepared by electron-beam evaporation of CeO2, where the growing film has been bombarded with oxygen ions. The packing density of the films has been increased from ∼0.55 without ion bombardment to unity with bombardment as determined by moisture adsorption measurements. The refractive index, extin…
Estimates of the indirect band gap for coherently strained alloys of ${\mathrm{Ge}}_{\mathrm{x}}$${\mathrm{Si}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ on Si〈001〉 are given for x in the range 0\ensuremath{\le}x\ensuremath{\le}0.75. The present results were obtained by combining x-ray diffraction data with relevant defor…
Transparent conducting films of cadmium stannate (Cd2SnO4), zinc oxide, and aluminum-doped zinc oxide have been made by a simple, economical electroless deposition technique. The as-deposited films of cadmium stannate have a 75% transmittance in the visible, 48% reflectance in the IR, and a band gap of 2.7 eV. Its res…
LiZnN, like other Nowotny-Juza filled tetrahedral ${A}^{\mathrm{I}{B}^{\mathrm{II}{C}^{\mathrm{V}}}}$ compounds, consists of a ${B}^{\mathrm{II}{C}^{\mathrm{V}}}$ zinc-blende lattice with the ${A}^{\mathrm{I}}$ atoms filling half of the available tetrahedral interstitial sites. Using band calculations we deduce an ``i…
A method for the vitrification of pure liquid water and dilute aqueous solutions is described which is the only one without a liquid cryomedium for heat transfer: rapid cooling of aqueous aerosol droplets on a solid cryoplate. This method is not limited to water and aqueous solutions, but can be used for the vitrifica…
The nucleation of persistent slip bands in stressed materials is described as a cooperative phenomenon for dislocation populations. It is the competition between their mobility and their nonlinear interactions (creation, annihilation, and pinning) which causes the instability of uniform dislocation distributions versu…
We present a theory of the first-order transition to the metallic state in polyacetylene in terms of a crossover from a lattice of charged solitons to a regular array of polaronlike distortions. The polaronic metal is shown to have a strong indirect attractive interaction, ${\mathrm{U}}^{\mathrm{*}}$\ensuremath{\simeq…
The Raman scattering from various model structures for amorphous silicon is computed. It is shown that the width of the ``optic peak'' increases roughly linearly with the rms bond-angle distortion \ensuremath{\Delta}${\ensuremath{\theta}}_{b}$ of the network. The experimentally observed linewidths lead to 7.7\ifmmode^…
The Raman spectrum of PbHPO 4 has been studied as a function of temperature between 10 and 320K (T c approximately=310K). A soft-mode is observed whose frequency has a temperature dependence that is close to, but not the same as, the spontaneous polarisation which follows the proton ordering. Several of the Raman line…
The authors argue that many phenomena associated with metal/nonmetal interfaces and similar situations with a large dielectric constant mismatch can be understood in terms of the image interactions due to charges in the nonmetal. The effects are additional to the traditional interactions, and are especially significan…
Debye relaxation behaviour is unique in the sense that all memory of excitation is instantaneously lost. It is shown that the presence of higher-frequency relaxations for components of the same dipole degrades this property by extending the memory into the timescale of relaxation, thus giving a nonDebye behaviour whic…
Bisphthalonitrile monomers were cured neat, with nucleophilic and redox co-reactants, or in combination with a reactive diluent. Dynamic mechanical measurements on the resulting polymers from -150 to +300°C turn up several differences attributable to differences in network structure. Rheovibron results were supplement…