Materials Literature
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Summary Three groups of minerals are discussed, which are typified by pyroaurite and sjögrenitc, hydrocalumite, and ettringite. All show interesting structural features. In the pyroaurite-sjögrenite group, brucite-likc layers carrying a net positive charge alternate with layers in which the oxygen atoms of carbonate g…
Abstract Edwards’s equilibrium theory of rubber elasticity is used to study the effect on the network elasticity of the consecutive addition and removal of cross-links under different strains. The treatment is compared with those of Flory, Scanlan and others based on classical rubber elasticity theory. For a composite…
Abstract : The physical-chemical thermal and optical properties of Bi2Te3 and solid solutions based on it are reviewed, as are the influences of defects and impurities. The technology of these materials is surveyed. The mobility and scattering mechanism of the charge carriers and the band structure are discussed. Ther…
The concepts involved in Frank's [1] formula and the treatment of surface dislocations by Bilby et al. [4] are combined to develop a vector equation for the closure failure associated with a boundary between crystals with different lattice parameters. The relation between the extended Frank's formula and Bollmann's wo…
The dispersion of the dielectric constant of triglycine sulphate (TGS) is investigated in detail by measurements up to 10 GHz. The dispersion can be well described by a Debye equation. The characteristic relaxation frequency f̃o=fσ (σs-σ∞) shows only in the ferroelectric region an evident temperature dependence. The e…
The conductivity of pure and doped (Mo, Ti) V2O5 single crystals is measured along the three crystallographic directions in the temperature range 90 to 350° K. For T < 140° K, it is shown that conduction can be considered as a variable range hopping between defect levels, situated in the neighbourhood of the Fermi-lev…
MnNiSi (Tc = 622 K), the major part of the MnCo1−xNixSi system, and MnFe0.5Ni0.5Si are ferromagnetic. Co and Fe substitutions decrease Tc, but increase the total moment. Compositions close to MnCoSi show antiferro- to ferromagnetic transitions with increasing temperature. MnCoSi and MnRhSi are antiferromagnetic. We br…
The temperature and concentration dependence of the interdiffusion coefficients as well as the activation energies for the FeNi, FeCo, and CoNi systems have been investigated over a wide range of temperature using electron probe microanalysis. The results are discussed on the basis of the equilibrium diagrams and t…
The infrared optical absorption coefficient for spherical particles coated with a dielectric mantel and imbedded in a nonabsorbing dielectric medium has been predicted based on calculations of the average dielectric function. The theory represents an extension of the continuum, volume-averaging model of Genzel and Mar…
Gallium telluride single crystals have been grown and cleaved to form thin platelet specimens. Small-area contacts on opposite faces produce threshold switching characteristics when high fields are applied across them, while large-area contact produce memory switching. Detailed measurements of conductivity under DC an…
The temperature dependences from 4·2 to 300 K of the seven adiabatic elastic constants of CaWO 4 have been determined by measurements of ultrasound wave velocities using the `sing-around' and pulse superposition methods. The adiabatic elastic constants have been calculated from the measured ultrasound wave velocities…
The kinetics of the solute effect on solvent electromigration and the vacancy-flow effect on solute electromigration have been analyzed. The Howard and Manning type analysis has been applied to the diffusion data of a number of solutes in Al, Cu, Ag, and Au for determining the required jumping-frequency ratios. The cr…
A neutron diffraction study of L-glutamine, C s H I o N 2 O a , has been carried out. Space group P212121; Z= 4; a = 16.020 (10), b = 7.762 (6), c = 5 119 (4) ,~. Full-matrix least-squares refinements, including anisotropic temperature factors for all atoms and an extinction correction, have led to a conventional R va…
The theory of x-ray photoemission (and related experiments) involving the excitation of a core state interacting with plasmons is presented. Specifically, the effects of the solid surface have been calculated, thus complementing the authors' previous calculation of the bulk effects. The strengths of the surface- and b…
Valence-band spectra of Cu, Ni, and Ag, obtained using x-ray photoemission, are compared with one-electron densities of states. Similar measurements on the CuNi and AgPd alloy systems are shown to be compatible with the predictions of the coherent-potential approximation.
An experimental examination of the spin forbidden transitions of molecular oxygen dissolved in various solvents and in the gas phase reveals the following selection rules governing the intermolecular enhancement of these transitions: (i) Nonheavy atom solvents selectively enhance the 1Δg← 3Σg− transition (factor of 10…
Mixtures consisting of conducting particles dispersed in an insulating medium are considered, and the electrical conduction which can occur by particles touching is related to the proportion of conducting material present in the mix, and its conductivity. It is found that limiting values of conduction can be obtained…
The previous microcoscopic models of photoemission are developed and reformulated in order to include inelastic scattering effects. A general expression is given for the photocurrent and its energy distribution (EDC). The problem of inelastic scattering is more thoroughly discussed in the case of electron-phonon inter…
The valence-band structures of MnO, CoO, NiO, CuO, ${\mathrm{Cu}}_{2}$O, Ni${\mathrm{Cl}}_{2}$, NiS, and KNi${\mathrm{F}}_{3}$ have been obtained by x-ray photoelectron spectroscopy. Band widths and positions are obtained, and are compared with the results of band-structure calculations. Bandwidths for the oxides are…
Between 30 and 290 K the thermal expansion of vitreous silica is shown to be particularly sensitive to thermal history. Values given for the linear coefficient α were determined relative to copper, and existing reference data for copper are discussed. α for silicon has also been measured relative to copper from 55 K t…