Materials Literature
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A high‐temperature X‐ray diffraction study of a high‐purity PbZrO 3 specimen at 25° to 236°C is reported. The symmetry of the perovskite sub‐cell of PbZrO 3 was determined unambiguously by observing the splitting of the line groups N = 12 and N = 16 when the diffraction pattern was indexed on the basis of the perovski…
After prolonged cyclic stressing in rolling contact, AISI 52100 bearing steel parts develop extensive regions of microstructural alteration, designated as white etching areas. These are oriented in predictable directions relative to the rolling track. Lenticular carbides are always associated with these areas. Evidenc…
Laminated, diatomaceous sediments of the Gulf of California consist of regularly alternating light-colored (diatom-rich) and dark-colored (clay-rich) laminae, approximately 2 mm. thick. The mean contents of opal (as diatom frustules) and quartz in the laminae, determined by X-ray diffraction methods, are: light-colore…
The effects of excluded volume on the existence and nature of a phase transition in an infinitely long double-stranded helical polymer are discussed in relation to the recent treatment of Poland and Scheraga, which showed that, if the entropy of a closed polymer loop of 2l links (corresponding to a diassociated length…
Possible patterns of vibration-induced splitting in the absorption band of localized electrons in solid are investigated within the Condon approximation. The modes of lattice vibrations around the imperfection which give rise to the level splitting of degenerate excited states are classified into active and potentiall…
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The elastic constants of zirconium carbide and titanium carbide were determined over the temperature range of 4.2° to 298°K using a pulsed-ultrasonic phase comparison technique, and are compared to previously determined values for uranium carbide. Since these carbides are of the NaCl structure, only three independent…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAbsorption Spectra of Octahedral Lanthanide HexahalidesJack L. Ryan and Chr. Klixbüll JørgensenCite this: J. Phys. Chem. 1966, 70, 9, 2845–2857Publication Date (Print):September 1, 1966Publication History Published online1 May 2002Published inissue 1 September 1966https://pu…
Fine metallic particles exhibit a peak of optical absorption around the frequency of the plasma mode. The absorption is broadened by coupling of the plasma oscillation with the individual electronic states which are quantized in discrete levels. Thus the broadening should not be interpreted as the resistance of free e…
The effects of couple stresses in fluids are considered. Linearized constitutive equations are proposed for force and couple stresses. A series of boundary-value problems are solved to indicate the effects of couple stresses as well as for experiments measuring the various material constants. It is found that a size e…
Abstract Durch Reduktion der Methoxycarbonylgruppen des Mesoporphyrin‐dimethylesters ( 4a ) wird das bisher unbekannte 1.3.5.8‐Tetramethyl‐2.4‐diäthyl‐6.7‐dipropyl‐porphin ( 5c ) erhalten. 5c läßt sich wie Octaäthyloporphin ( 7a ) als Kupferkomplex mit Hilfe der Vilsmeier‐Reaktion an einem meso ‐Kohlenstoffatom formyl…
Abstract A detailed analytical and kinetic study of the thermal decomposition of monosilane in the temperature range 375 to 430 °C and the initial pressure range 35 to 230 mmHg has been conducted. The gaseous products in the very early stages of the reaction are hydrogen, disilane and trisilane. In addition, later in…
Abstract The frequencies of the normal modes of vibration of lead telluride propagating in certain symmetric directions have been determined by inelastic neutron scattering techniques. The results have been used to deduce the parameters of rigid ion models and of shell models for the interatomic forces. The latter mod…
The Brillouin scattering spectra of crystalline quartz, fused quartz and Pyrex glass have been observed. The crystalline quartz spectrum contains three doublets corresponding to one longitudinal and two transverse acoustic modes, whereas the spectra of used quartz and Pyrex glass have one longitudinal and one transver…
The optical spectrum of Re4+(5d3) has been studied at 4.2°K in single crystals of K2PtCl6 and Cs2ZrCl6. The spectrum is characterized by extremely narrow lines in the region from 8500 to 36 000 cm−1. Vibrational structure is observed which is assigned to the odd modes of the ReCl62− complex. A crystal-field analysis o…