Materials Literature
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The oxidation kinetics of sintered α‐ and hot‐pressed SiC were investigated over the temperature range 1200° to 1500°C. Oxide thicknesses were measured by ellipsometry, interferometry, and profilometry. The two materials behaved similarly, exhibiting parabolic behavior for short times (up to 100 min) followed by decre…
Summary The adsorption of Zn 2+ , Pb 2+ , Cu 2+ , Co 2+ , and Cd 2+ (M 2+ ) by soils was measured at concentrations ranging from 10‐ 7 to 10‐ 2 M in 10‐ 3 to 10‐ 2 M CaCI 2 . Exchange between Ca 2+ and M 2+ , and solubility products [M 2+ ][OH − ] 2 indicate that M 2+ is not precipitated as hydroxide but is adsorbed o…
An extensive infrared investigation of the CO/Rh/Al2O3 system has revealed the presence of eight different CO/Rh species including two which have not been observed previously. It has been shown that Rh loading on an alumina support is more critical than reduction temperature in effecting infrared spectral changes in t…
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Evaluation of literature data combined with new experimental measurements shows that crystal structure is a basic factor in the grain‐size dependence of the critical fracture energy of ceramics. Notch beam (NB), double cantilever beam (DCB), and work‐of‐fracture (WOF) tests of materials having a cubic crystal structur…
Two methods have been developed for the microprobe analysis of Sodium in natural and synthetic glasses that exhibit time-dependent element migration during electron bombardment. A cryogenic method is based on the cooling of the sample to -90oC at which temperature sodium diffusion rate from the excitation volume is re…
The point defect model that was previously developed (1) to explain the growth kinetics of a passive film has been extended to account for chemical breakdown. This model provides quantitative explanations of the dependence of breakdown potential on halide concentration, and of the incubation time‐breakdown overpotenti…
A model based on the movement of point defects in an electrostatic field is proposed to interpret the growth behavior of a passive film on a metal surface. This model results in a logarithmic growth law. The theoretical equations derived from the model readily account for experimental data for the growth of a passive…
A review is given of elastic spin-polarised low-energy electron diffraction (SPLEED) from crystalline surfaces. For the two relevant spin-dependent interaction mechanisms, spin-orbit coupling, and exchange, dynamical theories are presented with emphasis on symmetry principles, potential models and multiple scattering…
Measurements of transient photoinduced optical absorption in $a$-${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ show that carriers thermalize within a distribution of localized states in the band gap. Photocurrent as well as photoinduced optical absorption transients are explained in a unified way with the multiple-trapping m…
The phenomenon of electromigration of atomic species during AES of glasses is discussed, and the induction time T i , before any migration occurs, is defined theoretically for the two possible directions of migration. Experimental Auger peak shapes are shown to exhibit a growing asymmetry with irradiation time, in suc…
Abstract Novel poly(keto‐amines), designated as poly(4‐iminophenacyls) are prepared by self polycondensation of 4‐aminophenacyl chloride under different experimental conditions. These polymers are insoluble in common solvents. The number average molecular weights of the polymer samples have been estimated by conductom…
It is shown that at low temperatures, phonon-assisted electron hopping between soliton bound states may be the dominant conduction process in a lightly doped, one-dimensional Peierls system such as polyacetylene. The presence of disorder, as represented by a spatially random distribution of charged dopant molecules, c…
Measurements of optical transmission and reflection spectra and Rutherford baokscattering experiments (RBS) are performed to investigate the influence of radiation damage on optical properties of silicon crystals implanted with Ar+-, P+-, and B+-ions at different temperatures (Ti = 77; 300; 500 K). At sufficiently low…