Materials Literature
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Samples of the cobalt-zinc ferrite series ${\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Zn}}_{x}{\mathrm{Fe}}_{2}{\mathrm{O}}_{4}$ have been studied by the M\"ossbauer-effect technique at 4 \ifmmode^\circ\else\textdegree\fi{}K, in magnetic fields from 0 to 80 kOe, covering the full range of zinc content. The cation distri…
The refractive indices of the ternaryA^{I}B^{III}C_{2}^{VI}semiconductors AgGaS2, CuGaS2, and CuInS2have been measured over the entire range of transparency of these crystals. The optical nonlinear coefficients for second-harmonic generation have also been determined. Three-frequency collinear phase matching is analyz…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEstablishment of an optical scale for Lewis basicity in inorganic oxyacids, molten salts, and glassesJ. A. Duffy and M. D. IngramCite this: J. Am. Chem. Soc. 1971, 93, 24, 6448–6454Publication Date (Print):December 1, 1971Publication History Published online1 May 2002Publish…
Certain general characteristics of the kinetics, mechanism, and nature of the primary step in chemical reactions initiated by mechanical action in various low- and high-molecular-weight substances have been examined. The formal kinetics of mechanochemical reactions occurring in constant and variable mechanical fields…
Photoemission energy distributions at high photon energies permit one-electron measurements of the electronic energy levels and level widths of chemisorbed gases on clean metal surfaces at fractional monolayer coverages. Chemisorbed CO on Ni exhibits energy levels at 7.5 and 10.7 eV below the Fermi level ${E}_{\mathrm…
Abstract Durch Einlagerung einer weichen Phase in feiner Verteilung lassen sich bekanntlisch die Zähigkeitseigenschaften von an sich spröden, harten Werkstoffen gezielt verbessern. Als wesentliche Voraussetzung für den Effekt der kautschukartigen Weichphase wird unter anderem stets verlangt, daß die beiden nicht misch…
Abstract A theory of the dielectric constant arising from electrons in localised states is developed. The theory applies to randomly distributed states, such as they might occur in disordered solids, impurities in crystalline semiconductors, polymer aggregates and other materials. The theory includes many-electron eff…
The nature and possible origins of the structural distortions in the neighbourhood of the Cr 3+ ion in MgCr 2 O 4 are discussed in the light of experimental evidence from optical, X-ray diffraction, infrared absorption and other investigations. The results of the analysis may have implications for other compounds with…
On the basis of the planar coupling factor it is shown that the maximum in the electromechanical activity at the morphotorpic phase boundary of Pb(ZrxTi1−x)O3 solid solutions is caused by a maximum of the dielectric constant. Starting from an expansion of the free energy similar to that introduced by Devonshire and po…
The ESR spectra of four radicals of the type RĊHCO2−, four of the type RĊ (O−) CO2−, and one each of the types R2ĊCO2− and ROHĊCO2− have been studied and the 13C hyperfine constants determined. The radicals were produced by continuous, in situ radiolysis of basic aqueous solutions of the appropriate acids. In all case…
It is shown that a pure thermal model, in the absence of significant heating of the electrodes, gives no negative differential resistance and no high-current filaments. When some electronic effects, such as space charge, narrow Schottky barriers, or field-enhanced conductivity, are explicitly introduced, negative-resi…
A further study is made of the properties of the simple tight-binding Hamiltonian for which Weaire has recently shown that a band gap exists in a tetrahedrally bonded solid regardless of its structure. An exact transformation of the density of states is found which relates it to that generated by a much simpler Hamilt…
The electronic band structure, charge density, and optical properties of diamond have been calculated using the discrete variational method in an ab initio approach with an LCAO Bloch basis set. This technique avoids most of the difficulties encountered with evaluation of the matrix elements of the Hamiltonian, and al…
The lattice thermal conductivity of germanium has been analyzed on the basis of the Callaway model in the temperature range 2-1100 \ifmmode^\circ\else\textdegree\fi{}K. At high temperatures four-phonon processes are seen to play an important role in the determination of the thermal resistivity of germanium. In order t…
The pyroelectric coefficient (at constant stress) of lithium sulfate monohydrate was measured over the temperature range 4.2-320\ifmmode^\circ\else\textdegree\fi{}K, in order to resolve a discrepancy between the results of Ackermann and those of Gladkii and Zheludev, and to extend the data to below 88\ifmmode^\circ\el…
Nuclear quadrupole resonance of $^{14}\mathrm{N}(I=1)$ has been studied for the two diatomic species $^{14}\mathrm{N}$-$^{14}\mathrm{N}$ and $^{14}\mathrm{N}$-$^{15}\mathrm{N}$ in solid $\ensuremath{\alpha}$-nitrogen. Spectra from carefully prepared and annealed samples display well-resolved intramolecular dipolar spl…
The photochromic properties of transition-metal-doped SrTi${\mathrm{O}}_{3}$ are studied using optical and electron paramagnetic resonance techniques. In addition to the double doped systems containing Fe + Mo, and Ni + Mo, which were treated briefly in earlier publications, the photochromic effect in SrTi${\mathrm{O}…
Crystals of triglycine sulfate (TGS) grown from solutions containing alanine are found to give biased ferroelectric hysteresis loops. The material is therefore always in a fully poled state when below its Curie point in the absence of large external fields. The values of ε′ and ε″ are lower than for pure TGS. Pyroelec…
The three-dimensional analog of Holstein's molecular crystal model is utilized as the basis for a study of the relaxation of the lattice after a small-polaron hop. In particular, it is shown explicitly that the time-dependent activationlike energy arising in the previously developed theory of correlated small-polaron…
Application of dc electric fields, at temperatures of \ensuremath{\sim}100 to \ensuremath{\sim}325\ifmmode^\circ\else\textdegree\fi{}C, to samples of SrTi${\mathrm{O}}_{3}$ doped with transition metals leads to the appearance of colored regions, characteristic of reduced material at the cathode and oxidized material a…