Materials Literature
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Abstract Average values for dispersion γ s d and polar γ s d contributions of the solid surface tension γ s γ s d + γ s p for poly(methylene oxide) (PMO) and Na‐treated polytetrafluoroethylene (PTFE) are determined by a new computational analysis of wettability data. PMO displays γ s d equals; 21.8 ± 0.9 and γ s p = 1…
Infrared spectra in the 0.5-50 m range have been measured on nesquehonite (MgCO 3 .3H 2 O, artinite (MgCO 3 .Mg(OH) 2 .3H 2 O) and hydromagnesite (4MgCO 3 .Mg(OH) 2 .4H 2 O). The CO 3 2- internal vibrations are sharp in hydromagnesite and unexpectedly broad and diffuse in artinite and nesquehonite. The OH - stretching…
A curve relating dispersed paramagnetic nitrogen concentrations in laboratory diamonds to their infra-red or ultra-violet absorption spectra has been obtained. Good quality laboratory diamonds ranging in size from 14 to 130 mg were used in this work. From this curve one can obtain dispersed paramagnetic nitrogen conce…
The effects of temperature, strain rate, and grain size on the mechanical properties of UO 2 were investigated using the four‐point bending technique. Strain rates were varied by two orders of magnitude, and test temperatures up to 1800°C were used. Data are presented on the ultimate tensile stress, yield stress, and…
Certains complexes hexacoordonnés de l'ion Fe2+ présentent une transition thermique du premier ordre entre deux états : low spin et high spin. Lorsque leurs paramètres (rayon ionique, énergie du fondamental, champ cristallin) diffèrent peu, une interaction d'Ising entre Fe2+ explique ce comportement.
A theoretical study is made of phonons in amorphous solids using a self-consistent phonon scheme. In treating the structural disorder inherent in the problem, a theory is formulated from the viewpoint of multiple scattering theory and designed to give phonon eigen-frequencies which are expressed in terms of many-body…
Exchange-striction effects have been studied in both the antiferromagnetic and paramagnetic states of NiO. Near-neighbor spin correlation functions as functions of temperature for various choices of $\frac{{J}_{2}}{{J}_{1}}$ have been calculated using Green's-function techniques and have been compared with our experim…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic exchange in transition metal complexes. V. Ferromagnetic spin coupling in a tetranuclear nickel(II) clusterAlvin P. Ginsberg, J. Aaron Bertrand, Roy I. Kaplan, C. E. Kirkwood, Raymond Leslie Martin, and Richard C. SherwoodCite this: Inorg. Chem. 1971, 10, 2, 240–246…
The molecular properties of optically active molecules are used to extend the molecular statistical theory of the nematic phase in order to explain the helical structure of the cholesteric phase. In order to account for these properties the dispersion energy between two molecules is calcualted taking into account not…
Abstract The shear creep and creep recovery behavior of narrow molecular weight distribution polystyrene samples of low molecular weight, 1.1 × 10 3 , 3.4 × 10 3 , and 1.57 × 10 4 are reported as a function of temperature, near and above the glass temperature. Time‐temperature equivalence for the total creep complianc…
An n-component substitutional solid solution in a perfect crystal can be characterized uniquely by n−1 independent composition functions. There are n(n−1)/2 distinct short-range-order parameters αij(i,j = 1,2,... n−1) corresponding to these (n−1) independent compositions. The SRO parameters are linearly but not quadra…
This paper reports polarized infrared and raman studies on zircon, zrsio 4 . The 36 k=0 modes of vibration are classified using group theoretical methods. The dielectric parameters epsilon minutes and epsilonseconds have been derived from the reflection spectrum using kramers-kronig theory. Measurements have also been…
The weight loss of Cr 2 O 3 in oxidizing environments (Po 2 = 1 to 10 −3 atm) at 1200°C was measured. Both hot‐pressed and sintered Cr 2 O 3 pellets were investigated in O 2 /Ar gas mixtures, and the dependence of the weight loss on the O 2 partial pressure, the gas flow rate, and the total pressure was determined ind…
A theory of electron scattering by complex atoms is developed in which the target atomic eigenstates and pseudostates are written as linear sums of configurations and the incident electron wave function is expanded in terms of orbitals which satisfy logarithmic boundary conditions on the surface of a sphere. The radiu…
Powder samples of high-density polyethylene and nickel of particle sizes Rp and Rm, respectively, were mixed and compacted at room temperature under a pressure of 1000 kg/cm2. Microscopic examination of polished sections of the compact, by reflected light, showed that the metallic particles did not penetrate the polym…
We assume that (1) the local state of order in the isotropic phase is a symmetric traceless tensor Qαβ, proportional to the anisotropic part of a tensor property such as the magnetic susceptibility; (2) the free energy may be expanded in powers of Qαβ and of its gradients. This allows a unified description covering th…
The spin-wave dispersion relation for the $c$ direction of dysprosium metal in the ferro-magnetic phase at 78\ifmmode^\circ\else\textdegree\fi{}K and in the helical magnetic phase at 98\ifmmode^\circ\else\textdegree\fi{}K has been measured by triple-axis neutron spectrometry. The energy gap measured in the ferromagnet…
According to Munz and Macherauch [1], the dependence of the mobile dislocation density on the strain rate can be estimated from the reduction of stress increments (Δτ/Δ ln \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop \varepsilon \limits^. $\end{document}) after a strain rate change. The high strai…
Single crystals of α-MoSe2 have been prepared which are superior to those grown using a chemical transport agent. The dielectric constant of α-MoSe2 has been measured over the range 0.5 to 3.5eV and a value for the direct optical band gap deduced from the observed exciton spectrum; this is compared with the measured a…
A high-temperature mass spectrometric investigation of the vaporization of titanium monosulfide, TiS(s), from 1700–2150°K has shown that the three principal vaporization reactions produce TiS(g), Ti(g) + S(g), andTi(g) + 12S2(g), the second being about four times as important as the first and both more important than…