Materials Literature
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Monte Carlo results are presented for the free energy and dielectric constant of systems of permanent dipoles disposed on the sites of simple cubic and face-centred cubic lattices as functions of the parameter ϑ = μ2ρ/kT. Alternative schemes are considered for taking account of the long-range character of the dipolar…
The hexagonal cell dimensions a and c of 2H-MoS2, 2H-MoSe2 and 2H-WSe2 have been measured over the temperature range 20 to 800 °C. In all three compounds a and c increased non-linearly with temperature, the linear thermal expansion coefficient of c being greater than that of a. Above 500°C the compounds begin to decom…
ABSTRACT Determinations were made of several physical properties of the viscid and frame silks of the orb-webs built by the spider Araneus sericatus (Cl.). Both types of silk show a breaking stress of approximately 1 GN/m2 and an initial resilience of approximately 0·35. The breaking extension ratio of viscid silk (λ…
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Procedures for the preparation of soluble collagen from rat skin and tail tendon were reviewed and revised to permit the preparation of native monomeric collagen with intact nonhelical ends. The degree of intactness was estimated from the tyrosine content, which is present only in the nonhelical ends, and by mobility…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of the quenching of the emission of substituted polypyridineruthenium(II) complexes by iron(III), chromium(III), and europium(III) ionsC. T. Lin, W. Boettcher, M. Chou, C. Creutz, and N. SutinCite this: J. Am. Chem. Soc. 1976, 98, 21, 6536–6544Publication Date (Pri…
A set of central interionic potentials for the rubidium halides is presented. These potentials, which are based on a shell-model description, are fitted to solid state data and are used in molecular dynamics simulations of the ionic melts. The partial radial distribution functions, the velocity autocorrelation functio…
The nature of the charge carriers in n-type BaTiO 3 is discussed in the light of recent investigations into their mobility (T<or=1500K) and defect chemistry. Evidence is found for small polaron formation. Mobility enhancement-probably due to correlated hopping-must be assumed in order to furnish a consistent explanati…
The ${[\mathrm{Li}]}^{0}$ center has been formed in lithium-doped single crystals of MgO by high temperature quenching. In contrast to the ${[\mathrm{Li}]}^{0}$ center formed by low-temperature $\ensuremath{\gamma}$ irradiation, the center formed by quenching is stable at room temperature. A heavy electron irradiation…
A pressure-induced tricritical point is indicated for ${\mathrm{KH}}_{2}$${\mathrm{PO}}_{4}$ near 2 kbar pressure. This estimate is based on analysis of our static dielectric data for pressures up to 3 kbar.
The existence of a hexagonal (wurtzite) form of silicon, similar to that form of diamond (carbon) observed in meteorites and in the laboratory, has been identified by x-ray diffraction in reaction-bonded silicon nitride containing unreacted silicon. The presence of this phase is due to stresses created in the silicon…
Polyphosphazenes are emerging as a new class of macromolecules that have an obvious future as technological elastomers, films, fibers, and textile treatment agents. However, they also possess almost unique attributes for use in biomedicine as reconstructive plastics or as drug-carrier molecules. Moreover, their possib…
With glass capillary pressure vessels it has been possible to study the effect of pressure on the temperature of maximum density (TMD) and on the "sharpness" of the density maximum in liquid H(2)O and D(2)O in the important but little-studied supercooled regime. A pressure of 1200 bars produces a 33 degrees C depressi…
High-purity Ni is used for quenching experiments in a He cryostat, the electrical resistivity being used as a defect indicator. The quenched-in resistivity recovers in two stages: a steep one, A, around 120°C with a decrease of 50% and a rather broad one, B, around 560°C with a decrease of 45%. The formation energy of…
Polarized measurements of the reflectance and temperature-modulated reflectance spectra of ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ in the range of 0.5-5.8 eV are reported. The experimental results strongly support the level scheme of Goodenough and are in good agreement with the theoretical model of Ashkenazi and Chuchem…
A high temperature vaporization study of the scandium–sulfur system has shown that a defect scandium monosulfide phase with composition Sc/S=0.8065 vaporizes congruently over the temperature range 1875–2220 K. High temperature mass spectrometric results show that the congruently subliming phase has two principle vapor…
This paper presents a study of the broadening and splittings of bound-hole excitation lines in silicon when the excitation energy is comparable to that of optical phonons. The approach utilized is a generalization of a similar study for donors in which the degeneracies of the ground and excited states do not play an e…
Hydrogen arrangements in two polymorphic forms, β 1 and β 2 , of V 2 H have been studied by powder neutron diffraction up to 200°C. The hydrogen atoms in β 1 -V 2 H are fully ordered in the specific o z -sites of the body-centered pseudo-tetragonal vanadium lattice ( c 0 / a 0 ≃1.1), forming a monoclinic superstructur…
The fundamental absorption spectra of evaporated thin films of La- and Ce-halides have been measured over a photon energy range from 3 to 40 eV. The fine structures occurring below the threshold in Ce-halides are ascribed to the 4 f →5 d transition of cerium ion. The Cl - L 2,3 absorption spectra of LaCl 3 and CeCl 3…
This is the first of a two part study of a statistical mechanical system that exhibits an isostructural phase transition at high density and pressure. Here, in Paper I, we consider a one-dimensional fluid; in Paper II we go on to treat the same system in three dimensions, using the approximation methods developed and…