Materials Literature
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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…
The electrical resistivity and thermoelectric power of ceramic samples of NiO doped with Li and Na are studied as function of temperature and dopant concentration. The resistivity ∂ is measured in the temperature range 100 to 700 K and thermoelectric power α in the range 100 to 300 K. The results obtained indicate ban…
A precise experimental diffractometric study of unit cell parameters of polycrystalline BaTiO3 in the temperature range from −170 to 220 °C is made, using an X-ray diffraction line refinement computer method. The values of unit cell volume jump, the widths of phase coexistence regions, and the hysteresis characteristi…
The EPR spctrum in γ-irradiated KIO2F2 crystals has been reinvestigated. Originally thought to be due to IO2F−, the spectrum has been reanalyzed and reassigned to the radical IO2. Improved principal values for the g factor and the 127I hyperfine and quadrupole interactions were obtained by the statistical technique of…
The x-ray diffraction pattern of the CCl4 plastic crystal (fcc), consisting of halos and a few sharp peaks, was observed by using an energy-dispersive method at −30 °C and the halo pattern was analyzed. The observed intensity was explained by the ’’head–tail head–tail model.’’ This arrangement is consistent with the l…
The E′4 center in irradiated α-quartz has been studied by single-crystal EPR. The unpaired electron is shared mainly by two silicon ions Si(1, 2) with the larger fraction on Si(2). The spin-Hamiltonian parameter matrices ḡ, Ā1H, Ā29Si(1, 2) at 40 K, as well as Ā29Si(1, 2) at 300 K, are reported. A model of the E4′ cen…
The optical absorption, emission, emission lifetime, and absolute quantum efficiency have been measured for chromium (III) in a wide variety of oxide and fluoride glasses. In all cases, the room temperature emission is dominated by inhomogeneously broadened 4T2 fluorescence, and the relaxation of this level is shown t…
The relations between electronic transport, the periodic lattice distortion (PLD) associated with charge-density waves (CDW), and disorder are studied experimentally in $1T\ensuremath{-}\mathrm{T}\mathrm{a}{\mathrm{S}}_{2}$. Disorder is introduced by means of electron irradiation which is able to displace lattice atom…
Near-normal-incidence reflectivity spectra of single crystals of MnP${\mathrm{S}}_{3}$, FeP${\mathrm{S}}_{3}$, and NiP${\mathrm{S}}_{3}$ have been obtained in the vacuum ultraviolet region of the optical spectrum. The spectra are interpreted using molecular-orbital ideas as well as simple physical and chemical argumen…
The structural phase transitions in the perovskite-type layer-structure compounds [N${\mathrm{H}}_{3}$${(\mathrm{C}{\mathrm{H}}_{2})}_{3}$N${\mathrm{H}}_{3}$]Cd${\mathrm{Cl}}_{4}$ (${T}_{c}=375 \mathrm{K}$), [N${\mathrm{H}}_{3}$${(\mathrm{C}{\mathrm{H}}_{2})}_{4}$N${\mathrm{H}}_{3}$]Mn${\mathrm{Cl}}_{4}$ (${T}_{c}=382…
The uniaxial stress and angular shear dependence of several extremal cross sections of the Fermi surface of the simple metal lead were obtained by a simultaneous measurement of the oscillatory magnetostriction and the de Haas---van Alphen torque. For six of the seven experimentally studied orbits all the uniaxial stre…
We report the polarized Raman spectra of vitreous ${\mathrm{Si}}^{18}$${\mathrm{O}}_{2}$ prepared by steam oxidation of Si in $\mathrm{H}_{2}^{}{}_{}{}^{18}$O. This yields the $^{16}\mathrm{O}$ \ensuremath{\rightarrow} $^{18}\mathrm{O}$ isotope shifts for all Raman- and nearly all infrared-active modes. The shifts of…
A single configuration model containing nonorthogonal magnetic orbitals is developed to represent the important features of the antiferromagnetic state of a transition metal dimer. A state of mixed spin symmetry and lowered space symmetry is constructed which has both conceptual and practical computational value. Eith…