Materials Literature
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Barium titanate doped with donors is a good n-type semiconductor, the conductivity of which, however, is considerably influenced by intrinsic defects always present in these materials. Therefore not only the equilibrium behaviour of these defects but also the defect formation and the defect diffusion play an important…
Data are presented for the refractive index of Irtran 2, a hot-pressed microcrystalline compact of ZnS, made by the Eastman Kodak Company, from 1 microm to 15 microm and from 93 K to 283 K. The values range from 2.35 at both high temperatures and short wavelengths to 2.12 at the opposite extremes. The average value of…
The controlled potential electrolysis of Ni(II) meso-tetraphenylporphyrin (Ni(II)TPP) gives at room temperature the corresponding metalloporphyrin π-cation radical [Ni(II)TPP] + • . Upon freezing a solution of the π-cation radical to 77 K an internal electron transfer occurs to give [Ni(III)TPP] + . A discussion of th…
Crystals of varying compensation mechanism (extra oxygen bridges or ${\mathrm{Co}}^{2+}$ substitution) and phase ($\ensuremath{\beta}$ or ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$) have been grown by adding cobalt oxide to a melt containing NaC${\mathrm{O}}_{3}$, ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, and…
The far-infrared conductivity of Na, Ag, Rb, and K $\ensuremath{\beta}$-alumina is measured from 10 to 200 ${\mathrm{cm}}^{\ensuremath{-}1}$. A broad band of absorption is observed whose detailed structure depends on growth conditions. The frequencies observed agree quantitatively with model calculations by Wang, Gaff…
An attempt has been made to understand the detailed form and phasing taken by the periodic-structural distortions (PSD) as developed in the various ${d}^{1}\ensuremath{-}{d}^{0}$ charge-density-wave (CDW) bearing materials. The diagrammatic mode of presentation which is used facilitates insight into the forces at work…
The transport properties of semimetallic Ti${\mathrm{Se}}_{2}$ are reexamined, and the limits of a two-band model are discussed. We conclude that the density of electrons and holes is 5 \ifmmode\times\else\texttimes\fi{} ${10}^{20}$/${\mathrm{cm}}^{3}$ to 10 \ifmmode\times\else\texttimes\fi{} ${10}^{20}$/${\mathrm{cm}…
A linear $\ensuremath{\gamma}T$ term is observed in the low-temperature specific-heat behavior of the nonmetallic vanadiumoxide bronzes of sodium and copper. The low-temperature magnetic susceptibility is equally anomalous and points to a singlet or diamagnetic ground state. It is postulated that the ${\mathrm{V}}^{4+…
Resonant Raman scattering of multiphonon modes has been studied in ${\mathrm{Cu}}_{2}$O in the region of its yellow and green excitonic series. Resonant enhancements of a large number of Raman modes have been observed. The experimental results have been interpreted quantitatively in terms of three kinds of exciton-pho…
Energy-loss spectra were measured by backscattering 500-eV electrons from films of W${\mathrm{O}}_{3}$ grown on single-crystal W(100), and from single crystals of ${\mathrm{Na}}_{x}$ W${\mathrm{O}}_{3}$ ($0.35<x<0.86$) and Re${\mathrm{O}}_{3}$ which were cleaved in ultrahigh vacuum. The spectrum of a crystal wit…
M2[Pt(CN)4]3⋅nH2O compounds (with M3+=Sm3+, Eu3+, Tb3+,...) represent a new solid state class for investigations of nonradiative excitation energy transfer. The donors are linear stacks (columns) of square planar [Pt(CN)4]2− complexes and the acceptors are rare earth ions which are located between the stacks. Radiatio…
An efficient and accurate numerical procedure is used to solve the HNC and RHNC integral equations for charged hard spheres, the so-called restricted primitive model (RPM) for electrolyte solutions and molten salts. The computed thermodynamic quantities and correlation functions are found to be in good but not excelle…
Spatial-period (320-nm) square-wave gratings fabricated on amorphous SiO2 substrates were used to produce uniform alignment of the director in nematic and smectic liquid-crystal layers. This demonstrates that molecular alignment can be achieved using surface structures fabricated by a planar process. A novel method of…
Recombination mechanisms for electrons and holes in chalcogenide glasses and amorphous silicon are discussed. In chalcogenides the model of charged defects is assumed to hold. Recombination can occur either radiatively by an electron-hole pair at a defect, or nonradiatively by self-trapping of a free exciton or by tun…
A molecular-dynamcis study of silver diffusion in superionic conductor $\ensuremath{\alpha}$-AgI is performed. Interionic potentials are constructed using Pauling's ideas of ionic radii. The diffusion constant for silver and its temperature dependence are in good agreement with experiment. Good agreement is also obtai…
A first direct observation of the '50K' structural transition in beta -phase palladium hydride has been made using neutron scattering. This observation, of a superlattice reflection at ( 1 / 2 10), allows us to conclude that the transition is essentially an order-disorder transition involving a local rearrangement of…
The role of boundary scattering of phonons in reducing the lattice thermal conductivity is investigated in silicon, germanium and silicon-germanium alloy. The theoretical model gives a satisfactory explanation to the reduction in thermal conductivity observed in thin undoped films of silicon compared to bulk material.…
Abstract The permeation characteristics of cellulose acetate membranes in separation of polymers from their aqueous solutions were investigated by changing the preparation conditions of the membranes, that are the solvent evaporation period and the casting solution composition consisting of a mixture of cellulose acet…
The EPR of ${\mathrm{Gd}}^{3+}$ impurities in the interconfiguration-fluctuation (ICF) host Ce${\mathrm{Pd}}_{3}$ is reported. The observed linewidth is consistent with an intrinsic relaxation rate proportional to $T$, where the proportionality constant is 3 times smaller than in the isostructural non-ICF host Y${\mat…
We have measured the carbon $K$ edge in graphite using inelastic-electron-scattering spectroscopy. The extended x-ray absorption fine structure is in good agreement with theory for the first-neighbor atoms at a distance of 1.42 \AA{}. The momentum dependence of the edge structure is in qualitative agreement with a sim…