Materials Literature
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Solid‐state substitution of Bi and Nb ions in the perovskite crystal structure of Pb(Ti 0.47 Zr 0.53 )O 3 was investigated by sample weight changes at 1150°C in an “equilibrium” PbO atmosphere. A model is discussed that includes the effect of charge neutralization, requiring weight losses for A‐site substitutions and…
Magnetization measurements of single crystal spheres of Y, Ce, Pr, Nd and SmCo5 compounds yield the magnetic moment per formular unit 7.9, 6.6, 10.4, 10.4 and 7.7 µB, respectively. The anisotropy constants K1 (0) and K2 (0) at 0 °K estimated from the K1 and K2 vs temperature curves measured are 6.5 and ~ 0, 5.5 and ~…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopy of rare earth oxide molecules in inert matrices at 4.deg.KWilliam Weltner Jr. and Roger L. DeKockCite this: J. Phys. Chem. 1971, 75, 4, 514–525Publication Date (Print):February 1, 1971Publication History Published online1 May 2002Published inissue 1 February 197…
<div class="htmlview paragraph">A mathematical model to predict the performance of catalytic converter systems that reduce the hydrocarbon and carbon monoxide contents in automobile exhaust gas is described. This model contains all the important system parameters and process variables, and it predicts the perfor…
The diffusion creep of polycrystalline materials must be accompanied by grain-boundary sliding in order that material continuity be preserved. Since both grain-boundary sliding and the addition of atoms to a boundary between two grains result in a relative translation of the grains, it is possible to regard the materi…
New experimental results on the electrophydrodynamic instabilites in nematics are presented. Joined with previously reported properties, they allow a general classification of these instabilities in term of one DC and two AC regimes. A quantitive explanation of the AC regimes is given, in the frame of the Carr-Helfric…
The interaction of a fast electron (energy \ensuremath{\gtrsim} 1 keV) with collective modes in a thin metallic or doped semiconductor film is studied, taking explicitly into account bulk and surface effects. Reducing the problem to an exactly soluble quantum-mechanical model, we obtain results to all orders of the in…
In order to characterize more completely defect structures typical of high dose neutron irradiation experiments, the determination of perfect dislocation loop geometry, as defined by the direction and sese of the Burgers vector b and the loop plane normal n, has been re-examined. The practical aspects of electron diff…
Diamond explosively synthesized from metal/graphite mixtures in shock configurations resulting in high temperatures, moderately high pressures, and relatively long holding times at pressure were investigated by electron microscopy and electron diffraction. Particles up to 5-μ diameter consist of a matrix of 10–40 Å, v…
The dispersion of a finite, dilatational stress wave propagating in a laminated composite was investigated both experimentally and analytically. The composite consisted of ten bilaminar plates oriented so that the plane of the plates was normal to the direction of the wave propagation. A flat plate accelerated by a co…
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…