Materials Literature
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The path maintaining rhombohedral symmetry in the transition from graphite to diamond which minimizes the energy at each value of the bond length between layers is determined. The energy barrier for this path is found to be 0.33 eV. The total energy of the solid is calculated using local-density-functional theory with…
Packings of spheres placed on vertices of two- or three-dimensional Penrose tilings arise in various models of glassy or ``quasicrystal'' metals. Such packings are described, with particular attention to the packing fractions and coordination numbers: In particular, one of the three-dimensional packings attains a pack…
Results of a renormalization-group analysis augmented by numerical calculations are presented for the electronic and phonon properties of a one-dimensional quasiperiodic lattice. Qualitative differences in the electronic and phonon band structure are predicted analytically and confirmed numerically. An exactly evaluat…
Thermal expansion of the hexagonal (4H) polytype of SiC was measured from 20 to 1000 °C by the x-ray diffraction technique. The principal axial coefficients of thermal expansion are expressed by the second-order polynomials: α11=3.21×10−6+3.56×10−9T−1.62×10−12T2, and α33=3.09×10−6+2.63×10−9T−1.08×10−12T2 (°C−1). The α…
In this paper, we carefully study the dielectric function of stage-1, acceptor-type graphite intercalated compounds (GIC's). We model the system by a superlattice of an infinite number of graphite layers, each of which has the band structure described by the two-dimensional calculation of Blinowski et al. Tunneling be…
In this (second) paper, quasicrystalline configurations of unit cells are analyzed for the cases of pentagonal and icosahedral orientational symmetry. We illustrate how two ideal quasicrystal structures with the same orientational symmetry and unit cells can be composed from very different local configurations of the…
In a recent paper, we introduced the concept of quasicrystals [Phys. Rev. Lett. 53, 2477 (1984)], a new class of ordered atomic structures. Quasicrystals have long-range quasiperiodic translational order and long-range orientational order. In the present paper and the following one, we discuss the details of our analy…
A model is described for the calculation of multipeak glow curves. A set of (k m +j m +2) equations are presented which describe the flow of electrons and holes between k m different electron trapping levels, j m different hole trapping levels and the conduction and valence bands. The model can be applied to complex c…
A simple method of determining the effective mass m* of free electrons in thin metal films (or the film thickness) only from the measured transmission of light in the range of the plasma reflection is discussed. The method is verified for gold films with thicknesses ranging from 7-40 nm. It was stated that the effecti…
It is shown that the humidity-sensitive surface conduction of porous alumina can be explained in terms of two complementary carrier-transfer mechanisms. At low humidities, a phonon-induced electron tunnelling is postulated between donor water sites; this tunnelling is assisted by anionic groups on the sensor surface.…
The electron density function rho(r) in a crystal determines its difaction pattern, that is, both the magnitudes and phases of its x-ray diffraction maxima, and conversely. If, however, as is always the case, only magnitudes are available from the diffraction experiment, then the density function rho(r) cannot be reco…
Infrared optical fibers composed of Te-based chalcogenide glass have been fabricated by using a high-speed drawing method. Transmission loss at 10.6 μm wavelength is reduced to 1.5 dB/m.
The total and differential atomic pair-correlation functions of an icosahedral (quasicrystalline) solid were determined for the first time, directly by the differential anomalous-x-ray-scattering technique using synchrotron radiation. The observed atomic distances involving uranium atoms in icosahedral ${\mathrm{Pd}}_…
Dynamic behavior of Brownian particles close to a wall is studied by photon correlation from an evanescent wave with variable penetration depth. Surface correlation spectra strongly differ from the bulk measurements and are completely interpreted in terms of the combined wall's mirror effect and evanescent-wave geomet…
We present a synchrotron-x-ray study of the smectic-C (${\mathrm{S}}_{\mathrm{C}}$) and smectic-I (${\mathrm{S}}_{\mathrm{I}}$) phase in a single-domain freely suspended film. Weak bond-orientational order in the ${\mathrm{S}}_{\mathrm{C}}$ phase evolves continuously into the ${\mathrm{S}}_{\mathrm{I}}$ phase so that…
We report x-ray reflectivity measurements on the free surface of dodecylcyanobiphenyl (12CB) at the isotropic to smectic-A phase transition. At about 10?deC above ${\mathrm{T}}_{\mathrm{IA}}$, smectic-A-like ordering develops at the surface while the bulk phase remains isotropic. The angular dependence of the specular…
The coefficient of thermal expansion (CTE) of a hot pressed Ta16W18O94 which was produced from Ta2O5 and WO3 powders was found to be −1.52×10−6 K−1 in the temperature range 180–330 K. Using the Ta16W18O94 and Super Invar powders, 50:50 volume percent metal-ceramic composites were made by the powder metallurgy techniqu…
Abstract The corrosion behaviour of tin in stagnant mono‐, di‐ and trichloroacetic acids solutions in the pH range 1–6 and at concentrations 4.0 to 5 × 10 −4 M was investigated. The results indicate behaviour that is generally the same but there is some dependence on the acid concentration and the pH value. In 4.0 to…
(1986). A Universal Computer Model for the Engineering of Weft-knitted Fabrics. The Journal of The Textile Institute: Vol. 77, No. 4, pp. 288-294.
The current densities of positive and negative ions i₊ and i-₋ in the back-discharge field of an electrostatic precipitator (ESP) are measured with a bipolar current probe. The ratio i₊/i- rises with increasing total current density i (= i₊ + i₋) in the streamer-mode back discharge, but it remains almost constant (10-…