Materials Literature
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The phase stability of Al as a function of pressure and the bulk properties at equilibrium are explored via a series of all-electron, non-muffin-tin, local-density-functional calculations for the fcc and bcc structures. The techniques used are the linear combination of Gaussian-type orbitals (LCGTO) techniques which w…
Fluorescence spectra have been analyzed at 4.2, 77, and 300 K and crystal field calculations have been performed on Na5Eu(MO4)4 (M=Mo, W) powders. The two sets of crystal field parameters are almost identical yielding a rms deviation of 5 cm−1. The values are (in cm−1): B20 =200 (180), B40 =−326 (−330), B44 =−863 (−85…
The sintering of ceramic oxide powders has been investigated using a high power CO2 laser as the heat source. The laser sintering method is very useful for the densification of oxides such as ZrO2, HfO2, and Y2O3 which have high melting points above 2000 °C. The new ceramic in the ternary system of (ZrO2-Y2O3-HfO2) pr…
The physical origin of eddy current losses in materials characterized by a very fine and complex domain structure is discussed, on the basis of a general statistical theory of losses developed in preceding papers. It is shown that the same process which is at the basis of the Barkhausen effect, namely the space-time c…
The generation of solitons and polarons and the decay of bipolarons into soliton-antisoliton pairs have been investigated with a self-consistent numerical calculation. The results are compared with the exact solutions at the continuum limit and justify the recent experimental suggestion of single-charge injection via…
In this paper we develop a modified self-consistent phonon approximation model which displays effects which indicate melting. The model is applied to hydrogen bond melting of poly (dG)⋅poly(dC) and predicts melting at 340 K. The calculation has no parameters adjusted to fit the melting, the hydrogen bond potentials ar…
The magnetoresistance of graphite exhibits a sharp increase at a certain critical field ${H}_{c}$ (${H}_{c}\ensuremath{\ge}22$ T), where ${H}_{c}$ is sensitive to temperature. This anomaly was ascribed to the formation of an electronic charge density wave by Yoshioka and Fukuyama (YF). To obtain an expression of ${H}_…
The atomic structure of ${\mathrm{Si}}_{x}{\mathrm{S}}_{1\ensuremath{-}x}$ glasses is investigated by the use of Raman spectroscopy. The compositional dependence of the microstructures of these glasses can be conveniently divided into three regions. At Si${\mathrm{S}}_{2}$, the glassy structure is composed of randomly…
The near IR (overtone) spectra of water, H2O–D2O solutions, and a glass-forming glycerol +D2O solution have been measured in the temperature range 80 to −30 °C (−120 °C for the glycerol +D2O solution) using emulsion samples to gain access to the deep supercooling range. At −30 °C the intensity attributed to weakly hyd…
Square arrays of 20–35-nm-diam gold particles with 50-nm spacings were formed on thick sapphire substrates by electron beam lithography. After annealing at 125 °C the particles had an approximately circular projection on the substrate with a slightly smaller dimension in the perpendicular direction as inferred from sc…
The results of an extensive vibrational analysis of tetramethyltetrathiafulvalene (TMTTF) and tetramethyltetraselenafulvalene (TMTSF) and of their radical cations are presented. The polarized infrared absorption spectra of oriented crystalline samples of neutral TMTTF and TMTSF (4000–80 cm−1) are reported and compared…
L'isomere Z cristallise dans P2 1 avec Z=2; affinement jusqu'a R=0,063. L'isomere E cristallise dans P2 1 avec Z=2; afinnement jusqu'a R=0,48 (P) cristallise dans P2 1 /n avec Z=4; affinement jusqu'a R=0,073. Les isomeres E et Z cristallisent dans le groupe d'espace monoclinique chiral P2 1 . L'isomere E violet pâle s…
The well-known restrictions on the possible shapes of electron energy bands arising from one-dimensional (1D) periodic potentials do not apply to chainlike physical systems such as polymers or molecular stacks, which are three dimensional objects periodic along a line. For such quasi-one-dimensional (Q1D) crystals, ba…
We present a study of angle-resolved photoemission of the layered compound Ti${\mathrm{Te}}_{2}$. The results are compared to augmented-plane-wave band-structure calculations which predict Ti${\mathrm{Te}}_{2}$ to be a semimetal with an overlap of valence and conduction bands of 0.6 eV. Reasonable agreement with the c…
We have measured by ellipsometry the dielectric constant of pure and heavily doped $n$- and $p$- type silicon from 1.8 to 5.6 eV. Both ion-implanted laser-annealed and bulk doped samples were used with concordant results. A red shift of the ${E}_{1}$ and ${E}_{2}$ critical-point energies, together with a decrease in t…
High-resolution infrared spectroscopy of the Si(100)2 \ifmmode\times\else\texttimes\fi{} 1 surface upon water exposure shows that, in the temperature range investigated (80 to 500 K), the adsorption is dissociative. Molecular water can only be adsorbed at low temperatures on a surface with saturated dangling bonds.
The graphitic phases of C and Si are studied with the use of the pseudopotential local-density-functional approach. For graphite, good agreement with experiment is obtained for the in-plane lattice constant, interlayer spacing, isotropic bulk modulus, and graphite-diamond structural energy difference. Graphitic Si has…
The refractive indices of a commercially available specimen of single-crystal MgF2 were determined for both the ordinary and extraordinary rays at selected wavelengths from 0.2026 to 7.04 μm. Measurements were made by means of the minimum-deviation method on a precision spectrometer near 19°C. The experimentally deter…
The effect of charge-transfer doping on the geometric and electronic structures of conjugated polymers has been investigated at the ab initio level with explicit consideration of the doping agents. Three systems were chosen for study as prototypical examples of conjugated polymers with nondegenerate ground states: pol…
Selection of materials and expected magnetocaloric effects are discussed for magnetic cooling applications at elevated temperatures (400–800 K). Various considerations result in the selection of rare earth-transition metal compounds such as Sm2Fe17−xCox for this task. These materials offer a wide range of suitable mag…