Materials Literature
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In order to resolve some of the experimental discrepancies existing between various published optical studies of diamond, absolute near-normal incidence-reflectance measurements have been taken on a polished type-I and both cleaved and polished type-$\mathrm{II}a$ diamond crystals. These measurements covered the range…
Large corrections to the x-ray intensities of the standard powder diffraction pattern of hexagonal AgI are proposed. Based on these intensities, it appears that some precipitates which have been described in the literature as pure hexagonal have actually contained about 30% of the cubic phase. Hexagonal AgI was produc…
Experimental results are presented on current-voltage relations in heteroepitaxial silicon films grown on sapphire. Above a threshold voltage a current is observed which is proportional to the square of the applied voltage, but inversely proportional to the square of the distance. It is interpreted as space-charge-lim…
Adiabatic elastic constants of LiCl, NaF, NaCl, NaBr, KF, RbCl, RbBr, and RbI were measured at 4.2 and 300\ifmmode^\circ\else\textdegree\fi{}K, using the ultrasonic pulse-echo technique. Data are also given for several of these materials, for the temperature interval 4.2 to 300\ifmmode^\circ\else\textdegree\fi{}K. It…
We have investigated the possibility of obtaining good approximate analytical expressions for the zero field splittings of cubic terms belonging to the t23 configuration. Spin—orbit, and trigonal and tetragonal field perturbations are considered, and a perturbation expansion based on a strong cubic field zeroth-order…
Relatively weak extrinsic luminescence bands observed at low temperatures (\ensuremath{\lesssim}80\ifmmode^\circ\else\textdegree\fi{}K) in silicon doped with several different donors and acceptors are described and identified with the following recombination processes: (1) Phonon-assisted decay of excitons bound to ne…
A detailed investigation has been made of the photoconductivity response of several types of natural diamond in the spectral energy range from 3.0 to 5.9 eV. Oscillatory structure in the photoconductivity beyond the fundamental absorption edge at 5.49 eV has been shown to be closely related to similar oscillatory stru…
Energy transfer from the sensitizers (S) Sb3+, Bi3+, or Ce3+ to the activators (A) Sm3+, Eu3+, Tb3+, or Dy3+ has been studied in four different host lattices, viz., YOCl, YBO3, YAl3B4O12, and YPO4. The efficiency of the energy transfer in these systems varies markedly. This is the case even for a given combination of…
Electron mobilities in reduced and doped SrTi${\mathrm{O}}_{3}$ have been deduced from measurements of the conductivity and Hall coefficient between 1 and 1000\ifmmode^\circ\else\textdegree\fi{}K. Above room temperature, scattering by the highest two longitudinal optical modes determines the mobility. Expressions base…
The hyperfine structure (hfs) and spin-lattice relaxation in the excited $\overline{E}(^{2}E)$ states of ${\mathrm{V}}^{2+}$ and ${\mathrm{Mn}}^{4+}$ in ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ have been studied by optical-detection techniques. This is an extension of an earlier study of EPR (electron paramagnetic resona…
The sharp absorption spectrum of antiferromagnetic ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ is investigated. The molecular-field approximation to the exchange interaction is shown to be inapplicable to the $^{2}E$ states. A modified exchange interaction is introduced via an effective Hamiltonian, and the resulting transi…
The impurity ion ${\mathrm{S}}_{2}^{\ensuremath{-}}$ has been introduced into six alkali-halide crystals: NaI, KCl, KBr, KI, RbBr, and RbI. The center is characterized by extreme $g$ anisotropy; in KBr, for example, the principal $g$ factors were 3.5037, 0.8434, and 0.8388. The first of these corresponds to the S-S bo…
Expressions for the temperature dependence of the magnetoelectric susceptibility parallel and perpendicular to the trigonal axis in ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ are presented. A two-sublattice model is used. The relation between the sublattice magnetization and the temperature is derived from experimental res…
Measurements of electron-bremsstrahlung cross sections have been made for incident electron energies of 1.0, 1.7, and 2.5 MeV and targets of Al, Cu, Sn, and Au. Data are included at angles of observation from 0\ifmmode^\circ\else\textdegree\fi{} to a limiting angle including more than 90% of the total emitted bremsstr…
Toller's group-theoretical analysis of kinematics is exploited to define a complete set of variables, each of independent range, for particle production of arbitrary multiplicity. In terms of these variables, the generalized Regge-pole hypothesis leads to a simple, unambiguous, and experimentally accessible prediction…
M\"ossbauer-effect measurements in external magnetic fields show that the magnetic structure of ferrimagnetic Ni${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$ is the collinear N\'eel type. Ni${\mathrm{Fe}}_{0.3}$${\mathrm{Cr}}_{1.7}$${\mathrm{O}}_{4}$ is shown to have a triangular structure with ${\ensuremath{\theta}}_{A}=20\i…
Experimental optical third-harmonic coefficients for inert gases are presented and compared with experimental Kerr coefficients and theoretical dc hyperpolarizabilities.Received 12 June 1967DOI:https://doi.org/10.1103/PhysRevLett.19.556©1967 American Physical Society
Essigsäurelösung bis zur Entfärbung titriert.Darauf gibt man 70 ml einer 0,5-n.methanolischen Jodlösung (Zusatz von 5 g KJ pro 100 ml) zu; man rührt weitere 10 Stdn.bei -40 °C und noch 2 Stdn.bei Zimmertemperatur.Das überschüssige Jod wird mit Natriumthiosulfat zurücktitriert.Die Lösung wird mit Natriumbicarbonat vers…
A study has been made of the wear of various hard steels sliding unlubricated in dry air and in dry carbon dioxide at temperatures up to 500°C. Over the range of loads and speeds employed the wear is of a mild character and the wear debris is of oxide particles, no metallic debris being formed. The characteristics of…
Films of As2Se3 and Sb2Se3 and their mixtures have been studied by electron microscopy and diffraction. On heating amorphous As2Se3 films no change occurs, but the Sb2Se3 films and mixtures of Sb2Se3 and As2Se3 transform to give small single crystals. These crystals have their c axes parallel to the substrate and give…