Materials Literature
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CONTENTS Introduction 154 1. Spin reorientation in rare-earth orthoferrites 154 2. Elastic properties of orthoferrites and features of their behavior near the spin-orientation temperature 156 3. Influence of pressure on the spin-reorientation temperature 160 Cited literature 161
Photoelectron spectra excited by x radiation are reported for the band-structure part on clean films of the rare-earth metals Nd, Sm, Dy, and Er. The dominant part of the spectra is due to excitation of $4f$ electrons. The spectra exhibit a complex and extended structure which is interpreted in terms of multiplet spli…
The infrared absorption and reflection spectra of the chalcogenide As2S3 and As2Se3 glasses and the absorption of As2S3 and As2Se3 crystals have been investigated in the wavelength range from 2 to 300 μm. The existence of the stretching and deformation vibrations of valent angles is shown. The optical constants n, k,…
Measurements of the Hall constant and mobility in the temperature range 81–1100 °K were carried out on n-type CdO single crystals with defect concentrations of 1.9–31.7 × 10 18 /cm 3 . Carrier concentrations were found to be independent of temperature, indicating complete ionization of the defect donors and semimetall…
The magnetoresistance, Hall effect, thermopower, thermal resistivity, and Nernst-Ettings-hausen effects are measured in magnetic fields to 10.3 T (103 kG) and at temperatures between 1.1 and 4.2 K. Samples are highly ordered pressure-annealed pyrolytic graphite. The major results are that majority-carrier electrons an…
Nearly perfect copper crystals with dislocation densities less than \ensuremath{\sim} ${10}^{3}$/${\mathrm{cm}}^{2}$ have been irradiated with fast neutrons at doses up to 4\ifmmode\times\else\texttimes\fi{}${10}^{19}$/${\mathrm{cm}}^{2}$, and the diffuse x-ray scattering resulting from the defects produced has been s…
The calculation of the chemisorption behavior of atomic H, C, N, O, and F on a graphite basal (0001) surface is examined with the CNDO (complete neglect of differential overlap) molecular-orbital scheme. This approach is a semiempirical approximation to the Hartree-Fock self-consistent field procedure, in which the Ha…
The effects of ultrasound on the optical properties of an aligned layer of nematic liquid crystal are described. It was observed that the birefringence of a normally oriented nematic liquid crystal was a function of the acoustic energy, and that with sufficient incident acoustic energy, a scattering phenomenon similar…
A technique for the preparation of pinhole-free glass films on porous substrates is described. The permeabilities of He, Ne, Ar, Kr, and D2 and the diffusivities of Ne, Ar, and D2 in the films are reported. The temperature range studied for He, Ne, and D2 was 25–500°C, while the range for Ar and Kr was 650–920°C. Acti…
Further evidence is presented to show that when cellulose is heated it undergoes two competitive reactions. The actual sequence of these is clarified, being different from that previously postulated. The natures of these reactions are studied, activation energies are determined, and their possible mechanisms are sugge…
The thermal conductivity of several NaF crystals of varying purity has been measured between 2 and 100 \ifmmode^\circ\else\textdegree\fi{}K. The full Callaway formalism is employed to derive phonon-phonon scattering rates from the thermal-conductivity data. The data can be fitted above 37 \ifmmode^\circ\else\textdegre…
A new electro-optical effect in twisted nematic liquid crystals is described which allows variation of the rotation of linearly polarized light continuously from 0° to 90°. It requires lower voltages than other electro-optic effects.
Abstract Für die Polymerisation von Lactid geeignete Initiatoren sind: Diäthylzink, Triäthylaluminium oder Zinntetrachlorid; folgende Verbindungen waren unwirksam: Triäthyloxoniumtetrafluobrat, Tropyliumtetrafluoborat, Tritylumhexachloroantimonat. Phenyldiazoniumhexafluophosphat oder Aluminiumtrichlorid. Die Polymeris…
Abstract The shape and forces of axisymmetric menisci have been calculated for sessile drops, pendant drops and liquid bridge profiles. The tables of Bashforth & Adams have been extended into the liquid bridge region by generating profiles beyond the 180° angle of their study, and into regions covered by a much wi…
Saturation magnetization was measured for a number of single crystals of hcp Co-base dilute alloys containing 3d-transition metal impurities such as Cr, Mn, Fe, Ni and Cu. The measurements were made with an induction magnetometer at 300 °K and 77 °K in fields up to 21 kOe in the directions of easy magnetization. The m…
Continuous-filament rayon yarns were subjected to an acid-catalyzed cross-linking treatment using dihydroxydi methylol ethyleneurea under pad-dry-cure conditions to two levels of add-on. The stress-strain curves of these yarns were measured at a constant 40%/min rate of extension in the dry (65% RH and 70°F) and wet s…
The magnetic properties of the spinels M1/2In1/2Cr2X4 with M = Cu or Ag and X = S or Se were investigated. In the sulphides the Cr spins order antiferromagnetically at TN = 40 °K for M = Cu and at TN = 17 °K for M = Ag. No spin ordering above 4 °K was observed in Cu1/2In1/2Cr2Se4, while Ag1/2In1/2Cr2Se4 is ferromagnet…
Powder neutron diffraction measurements have been performed on RbCoBr3. The results indicate that at TN = 36 °K, the compound exhibits a transition to an antiferromagnetic phase in which the spins are alternately aligned along c with a (+ + —) configuration for the three spins in the basal plane. This is in contrast t…
The magnetic moment of cobalt(II) fluorosulfate has been measured over the temperature range 312 to 120 °K and the results agree with theory for cobalt(II) in a regular octahedral ligand environment with λ equal to the free-ion value and no reduction in the magnetic moment due to electron delocalization. From its elec…
Expressions are developed for the orientation dependence of the nuclear quadrupole spin-lattice relaxation in crystals. Restrictions imposed by crystal symmetry are tabulated for the thirty-two nonmagnetic point groups. The possibility of distinguishing between different relaxation processes by means of orientation me…