Materials Literature
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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…
Abstract As an introduction, the general thermodynamic treatments for binary cation exchange are reviewed. The normal choice of standard states for the cations in the clay phase, and commonly used thermodynamic formulations with different scales of measurement are both discussed. The definition of standard states for…
Abstract Kandites, smectites and vermiculites all form interlamellar inclusion complexes. A comparison has been made between sorption in zeolites, clay minerals and clathrates. In smectites and vermiculites sorption isotherms reflect in contour and behaviour three situations. Kandites show only the first of these, in…
Abstract The paper reviews the structures and crystal chemistry of clay minerals, including interstratified minerals and related phyllosilicates. Brief accounts are presented of the disordered structures encountered in the different mineral groups and a conceptual structural model for interstratified minerals is outli…
Abstract Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for die origin of clay minerals in nature. Several of these possibilities are discussed in term…
Abstract The physicochemical properties of smectite clay minerals that determine their industrial utilization are reviewed. Smectite is the name used for a group of phyllosilicate mineral species, the most important of which are montmorillonite, beidellite, nontronite, saponite and hectorite. These and several other l…
A theory of the magnetisation process in ferromagnets, based on existing ideas of domain rotation and domain wall motion is presented. This has been developed via a consideration of the various energy terms into a mathematical description of the process leading to an equation of state for a ferromagnet. The differenti…
The magnesium ferrite-aluminate series MgAlxFe2-xO4 (x=0.2, 0.4 and 0.7) has been synthesised, the lattice constants determined and the applicability of Vegard's law has been tested. The Mossbauer spectra have been recorded from 77K to a temperature well above the Neel point. The Neel temperature decreases linearly wi…
The well known 2.8 eV luminescence band in quartz has been studied using optically detected magnetic resonance (ODMR). A triplet state with a very large fine-structure splitting is found to contribute to the emission. The principle axes of the triplet are identified. The possibility that the luminescence originates in…
Lanthanum strontium vanadate, La 1-x Sr x VO 3 , has been studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) and high-resolution electron energy-loss spectroscopy (HREELS) over a composition range 0<x<0.3 embracing the metal-nonmetal transition (MNMT) at x approximately=0.22. XPS confirmed that…
This paper presents a review of our current understanding of environmentally induced slow crack growth in glasses, single crystals, and polycrystalline ceramics. It is shown that the rate of crack growth is controlled by the chemical activity of the active species in the environment as well as by the stress intensity…
Simple methods are described to evaluate quantitatively the influence of charge-density-wave fluctuations on the thermodynamics of quasi one-dimensional conductors, and are applied to experimental data for ${\mathrm{K}}_{0.3}$Mo${\mathrm{O}}_{3}$. These fluctuations are found to affect strongly the magnetic susceptibi…
Predictions of the possible post-transition symmetries of an R3̄c zone center continuous phase transition are made using recent extensions of the Landau theory. The Landau theory is summarized and direct group theoretical methods are applied to the R3̄c phase. General techniques for solving systems of nonlinear polyno…
Abstract Diffusion of m‐sulfobenzoic acid in nylon 6 was measured by using the S‐35 labelled acid as a tracer. A multimodal mechanism, identical to that in a preceding paper on sorption, was assumed, according to which the protonated acid diffused by dissolution, and the two dissociated acids diffused by competitive i…