Materials Literature
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We discuss the nature of the lattice instability in a highly disordered quasi-one-dimensional conductor, where the electronic states near the Fermi energy are localized in space. The resulting lattice and charge-density distortions are random in space and are frozen. The mathematical and physical similarities of this…
The optical properties of MgCl 2 have been studied by means of reflection spectra in the region from VUV to XUV, absorption spectra in the VUV region, XPS and UPS spectra. In order to interpret the experimental results, the electronic band structure of MgCl 2 has been calculated by means of the tight binding method fo…
The effect of intermolecular interaction on the Raman spectrum of two modes which are in Fermi resonance has been investigated theoretically. The theory includes the resonance exchange of vibrational energy as well as the inter- and intramolecular Fermi coupling interaction and is expected to be a realistic model for…
High-resolution angle-resolved x-ray photoemission (XPS) valence-band spectra from a clean W (001) single crystal have been observed to show strong spectral variations both with electron-emission direction and temperature. The spectral changes with direction are in very good agreement with the predictions of a simple…
A molecular dynamic calculation on vitreous B2O3 reveals a structure in which boron is trigonally coordinated to oxygen. Boron atoms are at the center of approximately regular triangles. The triangles are connected at apices to form a three-dimensional network of interconnected ribbons and sheets. No tendency to form…
A series of molecular-dynamics calculations has been carried out to examine melting in the classical Gaussian core model at reduced density ${\ensuremath{\rho}}^{*}=0.2$. The stable crystal form at this density is body-centered cubic. Thermal equilibrium values of mean-square particle displacement have been evaluated…
The effects of supporting materials (Al 2 O 3 , SiO 2 , TiO 2 ) on the catalytic activity and selectivity of V 2 O 5 in the reduction of NO x with ammonia are reported. The adsorbed state and the reactivity of the surface species were examined by an ir spectroscopy together with volumetric measurements, and the electr…
The quadratic response formalism is used to derive a general expression for the Auger electron current in the limit of high energies of both photo- and Auger electrons. The Auger decay of the initial core hole is treated to all orders in the decay rate. General formulas for the first and second moments of the Auger sp…
Paraphenylene oligomers (biphenyl, p-terphenyl, p-quaterphenyl, p-quinquephenyl, p-sexiphenyl) form electrically conducting complexes with AsF5. Prolonged exposure to AsF5 causes a polymerization of these p-phenylene oligomers to give highly conducting charge-transfer complexes of poly(p-phenylene). Conductivities as…
The optical transition 2 F 7/2 → 2 F 5/2 of Yb 3+ in the antiferromagnet YbCrO 3 has been studied. The exchange splittings for the ground and excited Kramers doublets were observed in the antiferromagnetic state. From the analysis of the splitting of the ground Kramers doublet as a function of applied magnetic field,…
Infrared absorption spectra are reported for matrix isolated (CuCl)n, (CuBr)n, (AgCl)n, (AgBr)n and for mixed clusters with composition CunClmBrn–m. Silver halide clusters with n=1 to 3 are already present in the vapor in equilibrium with the melt. The monomer and dimer forms of the copper halides could be produced on…
We report the polarized Raman spectra, the infrared reflectivity, and the infrared dielectric constant of vitreous ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$, for vibrational frequencies up to 1800 ${\mathrm{cm}}^{\ensuremath{-}1}$. Longitudinal- and transverse-mode frequencies are identified. The dominant Raman line, at 80…
High-pressure resistivity measurements on mixed-valence TmSe indicate a new electronic phase transition near 30 kbar at liquid-helium temperature. In the paramagnetic phase, the $\ensuremath{\rho}\ensuremath{-}T$ curve shows unexpectedly small pressure dependence, in contrast with the predictions of a simple valence-c…
The low-temperature tunneling levels observed in glasses are discussed in terms of the free-volume model. As the system falls out of thermodynamic equilibrium near its glass transition temperature ${T}_{g}$, liquid clusters are frozen in. This Letter proposes that voids are formed within the liquid clusters as they in…
A major part of the giant Raman scattering by adsorbed molecules on a Ag-island film is shown to be due to the large increase in the electric field at the molecules and to the large electric dipole moment of the molecule-metal-island complex that result from the excitation of the transverse collective electron resonan…
The low-temperature thermal conductivity of lithium nitride (Li 3 N) shows a temperature dependence which is typical for a good dielectric crystal with K(T) varies as T 3 below about 1.5K. Its absolute value, however, is about 2.6 times smaller than expected. A quantitative analysis shows that this extra phonon scatte…
The authors have derived a rotationally invariant kinetic exchange interaction between strongly correlated electrons in a doubly degenerate narrow band with arbitrary band filling. The results are expressed in terms of the global operators characterising the spin and the orbital dynamics. The effective Hamiltonian pro…
The variation of viscosity with temperature has been determined over a wide range of temperature for a Muong Nong tektite material. The viscosity at the liquidus temperature of 1320°C is about 2×10 4 P. Crystallization heat treatments in the range of temperature between 900° and 1300°C does not produce significant cry…
An experimental study of electrostatically stabilized disclination walls is reported in the two-dimensional director field of freely suspended ferroelectric smectic-$C$ films. This Letter presents measurements of the dependence of the wall width on applied field and the collapse rate of walls forming closed circular l…
The initial burst and the diffusion of fission produced Xe were investigated on UC2 irradiated to thermal neutron doses between 2.1 x l014 and 1.3 x 1016 fission/cm8. In heating-runs with 5 and 10°C/min and below 1,000°C, the burst revealed three steps at around 200, 400 and 600°C (in 5°C/min heating run), to which ac…