Materials Literature
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The dislocation mobility in zinc single crystals was investigated by measuring the shear modulus changes at frequencies of ≈ 10 Hz over the temperature range from 100 to 300 °K. The activation parameters of dislocation motion in basal (0001) 〈11―20〉 and pyramidal {11―22} 〈1123〉 slip systems were determined. From the r…
The problem of the current–voltage characteristics of thin semiconducting films has been investigated. The sandwich configuration of films with metal electrodes was used and measurements were performed by increasing and decreasing the current and voltage, respectively. It is shown that there is a hysteresis of the cur…
The author has used Gaussian wavefunctions in a study of the F t centre in MgO and CaO. It is shown that Gaussian wavefunctions are very suitable for defect centre calculations because the integrals over the Madelung potential may be obtained analytically using Ewald's method of lattice summation. The calculation of B…
An expression is developed for the optical dielectric constant of a medium containing submicroscopic voids. For an absorbing host medium, voids introduce additional optical structure resembling that due to surface roughness. Void resonance absorption may account for unexplained structure recently reported in the optic…
Optical rotatory power (ρ = ± 5°35′/mm for λ = 6328 Å) was found in the Czochralski-grown ferroelectric crystal 5PbO·3GeO2. Reversal of the ferroelectric spontaneous polarization Ps caused the enantiomorphic transformation of the crystal and consequently the change in the sign of the optical rotatory power. The gyrati…
The contribution of scattering to the total attenuation coefficient for x rays is considered in crystalline materials. Calculated values of the coherent-scattering coefficient for four commonly used wavelengths and for a number of cubic elements from $Z=6$ to $Z=42$ are presented. Measured attenuation of $\mathrm{Mo}K…
Preliminary crystal-structure data for L-arginine HCI,, L-cysteine, DL-lysine and DL-phenylalanine have been derived from an analysis of their powder patterns. L-arginine HC1, crystallized from water, is tetragonal; a= 13-95 (4), c= 10.57 A, space group P422 and Z=8. L-cysteine and oL-phenylalanine are monoclinic. L-c…
Using the Born-von Karman and rigid-ion models of Elcombe for the optical phonons in $\ensuremath{\alpha}$-quartz, we have analyzed the Raman spectra of isomorphic AlP${\mathrm{O}}_{4}$ (berlinite). The resulting analysis yields several physical parameters which are not accessible to any other experimental measurement…
Filaments have been observed in VO2 coplanar thin-film devices and their I-V characteristic investigated. An analysis of the evolution of the temperature profile in the VO2 film is given.
We develop a model for simple diatomic crystals in which two effective-charge parameters are associated with the infrared-active optical-phonon mode. One of these is ${e}_{T}^{*}$, the macroscopic effective charge. The definition of the second charge, here designated as ${e}_{l}^{*}$, the localized effective charge, i…
The x-ray photoelectron spectra of the oxygen 1s level of olivines contain a single component whereas those of pyroxenes contain two components with an intensity ratio of 2:1 and an energy separation of about 1 electron volt. We interpret these two components to be the result of the binding energy differences between…
Craters produced by, missiles with oblique trajectories and kinetic energies between 2.1×1014 and 81×1014 ergs produce craters 2 to 10 meters across. The craters and their ejecta are typically bilaterally symmetrical about the plane of the trajectory. Crater dimensions are strongly dependent on target material and kin…
The changes in refractive index caused by shock compression have been determined for tektite, soda-lime, and silica glasses shocked to pressures up to 460 kb. For shock compression below 80 kb for fused silica and 40 kb for tektite and soda-lime glasses, compression is reversible as the refractive indices are within 0…
Spherulites are clusters of confocally radiating crystals that, contrary to the implication of their name, are not commonly spherical but usually resemble sheaves of wheat tied at the center. The variation of morphology from the wheat sheaf to the spherical spherulite and the transition of growth conditions from the s…
Chemically activated electroadhesive pads on spacecraft surface, allowing astronauts to maneuver or work in zero gravity environments
Abstract The growth of crystals of calf rennin (chymosin, † EC 3.4.4.3) and the control of nucleation to produce crystals of desired size, are described. Only one stable species, orthorhombic rennin I, has been found, but a metastable monoclinic species, rennin II, appeared on one occasion in a solution nearly saturat…
One of the precesses which may be observed in ${e}^{\ifmmode\pm\else\textpm\fi{}}{e}^{\ensuremath{-}}$ colliding-beam experiments is the deep inelastic electron-photon scattering. We examine the feasibility of such an experiment assuming an appropriate scaling limit.
The energy loss of 5-eV electrons reflected from clean and from oxidized (111) silicon surfaces has been investigated. A surface phonon with $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\approx}55$ meV, $k\ensuremath{\approx}0$ is found at the clean surface. After exposure to \ensuremath{\cong}${10}^{\ensuremath{…
Abstract A direct electrochemical preparation of polybutadiene to a predetermined molecular weight distribution has been achieved. Butadiene is a good model compound, inasmuch as the rate of electrochemical initiation is high relative to the rate of propagation. Rate constants for the temperature interval of interest…
Meaningful high resolution microscope of specimens that are sensitive to radiation damage is limited in resolution by considerations of statistics and contrast in the image. The product of contrast, C, and resolution, d, must satisfy the inequality where S/n is the minimum acceptable ratio of real contrast to statisti…