Materials Literature
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YAG and LiNbO3 are X-ray coloured at LNT and the absorption spectra are measured. The glow curves of thermal bleaching and thermoluminescence of these crystals are determined. The former permit a separation of different absorption components by heating in steps. For LiNbO3 and YAlO3 the linear dichroism of these compo…
The Mössbauer effect has been used to study the effect of varying the Fe to Ni ratio in the compounds Dy(Fe1−xNix)3 and Y(Fe1−xNix)3 on the Fe57 hyperfine field and the ordering temperature. The results are compared with other recent studies and related compounds.
There is a unique activation energy for superplastic flow, which may be determined from tests performed either at constant strain rate or at constant stress. Three methods are described for obtaining the activation energy, and the procedures are illustrated using experimental data for the Zn–22% Al eutectoid alloy. It…
An analytical equation for the Helmholtz free energy of a pure fluid of particles interacting according to a square-well potential is derived from the Barker–Henderson perturbation theory. An analytical treatment of the solution of the Percus–Yevick integral equation for a fluid of hard spheres yields an analytical ap…
The spatial distribution of the energy deposited by kilovolt electrons moving through gaseous molecular nitrogen was measured. The range of electrons of initial energy 300 eV to 5 keV was obtained and can be expressed by the formula R=K1+K2EA1−K3EA2, where R is the range, E is the initial energy of the electrons, and…
We have studied the thermoelectric power of an infinite Hubbard chain with arbitrary electron density in the strong-coupling limit. Calculations were carried out for the simple Hubbard model and in the atomic limit of an extended Hubbard model having an arbitrary nearest-neighbor repulsion. We compare the results to t…
Neutron inelastic scattering measurements of the phonon dispersion relation of GaSe have been analysed in terms of a simple axially symmetric Born-von K\'arm\'an force-constant model. The results show that the interlayer interaction is very weak compared with the intralayer ones. The model obtained from this analysis…
Measurements of the time dependence of the coloration (formation of HxWO3) of amorphous films of WO3 are described and analyzed in terms of a barrier for current flow at the WO3-electrolyte interface. A novel feature is that as coloration proceeds, the chemical potential of hydrogen in the HxWO3 increases, opposing fu…
The well-known specific-heat anomaly in amorphous dielectrics and their universal thermal conductivity have been carefully studied for the same wide variety of glasses as reported previously. The present studies have shown that the thermal conductivity is entirely insensitive to variations of the chemical purity or th…
A method of hydrogenating sputtered amorphous Ge has been developed for systematically studying the variation of the electronic properties with the number of dangling bonds. The role of incorporated hydrogen was established by the correlation of x-ray diffraction, electron paramagnetic resonance, and optical spectrosc…
Elementary potentials are applied to a study of hexagonal boron nitride. All second- and third-order elastic constants are calculated and compared with the available experimental data. The planar bending constant, important to the semicontinuum theory for layered crystals, is obtained from a simple model.
Photoemission measurements have, for the first time, been extended to photon energies between 100 and 300 eV. Results from polycrystalline gold show amplitude modulation of the $5d$ peaks in the valence band for $100<h\ensuremath{\nu}<200$ eV. The photoionization cross section of the $4f$ electrons is mapped out…
The hydrodynamic equations for solids are derived from the connection between hydrodynamic variables (and linearized hydrodynamic modes) and continuous broken symmetries. A simple fluid has five hydrodynamic variables (and modes), one for each conservation law (mass, three components of momentum and energy). As pointe…
The nature of the ground state of the V centre in ionic oxides is discussed, where two holes are trapped by a cation vacancy. Experiment appears to indicate an S=1 ground state for BeO and Al 2 O 3 and possibly ZnO, with S=0 in MgO and CaO. Simple theoretical arguments suggest S=0. It is shown that a weak mixture of (…
Citrate synthase from Escherichia coli enhances the fluorescence of its allosteric inhibitor, NADH, and shifts the peak of emission of the coenzyme from 457 to 428 nm. These effects have been used to measure the binding of NADH to this enzyme under various conditions. The dissociation constant for the NADH-citrate syn…
Abstract The Lygaeid bug Spilostethus pandurus (Scop.) prefers to feed on the leaves of the Asclepiadaceous plant Calotropis procera. The insect possesses two dorsolateral prothoracic glands, the secretion of which proved repugnatorial and unpalatable to predators. S. pandurus can make use of the cardiac glycosides pr…
A new Monte Carlo approach to the direct simulation of scattering process of a penetrating electron in matter has been attempted. The theoretical stopping powers for elementary excitation processes (conduction-electron, plasmon and L-shell electron excitations) were used instead of Bethe's stopping power equation to d…
INTRODUCTION This article is concerned with the hardening of solids, mainly metals, by various arrays of solute atoms. Random solid solutions, coherent and incoherent precipitates are considered. In addition, some attention is given to alloys containing long-range order, which have recently been studied in detail. The…
Abstract This paper attempts to improve several weaknesses in the classical theories of rubber elasticity. It develops a formulation of the statistical thermodynamics of amorphous materials analogous to the Gibbs formalism for conventional statistical mechanics. This then permits the replacement of ‘phantom chains’, i…
We report a new method of measuring thermal-equilibrium properties of vacancies in metals through current-noise measurements. Aluminum noise spectra taken at 435 and 475\ifmmode^\circ\else\textdegree\fi{}C directly yield vacancy lifetimes ${\ensuremath{\tau}}_{0}=4.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{…