Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
The FMR (ferromagnetic-resonance) measurements were performed in single crystals of silicon-iron, nickel-iron, nickel, and hcp cobalt in the frequency region 8-140 Gc/sec at room temperature. The samples, in the form of thin discs, were statically magnetized parallel to the plane of the disc. Their thickness was at le…
Measurements of the absorption between 0.3 and 1.0 mm have been made on NaCl, KCl, KBr, KI, NaI, and LiF between room temperature and 15\ifmmode^\circ\else\textdegree\fi{}K. Present theory explains the absorption in this region as arising from "vertical" transitions from one phonon state to another with the same wave…
The spin-wave thermal conductivity of ferromagnetic insulators with magnetic scattering is investigated. The role of magnon-magnon interactions is clarified. The magnetoelastic coupling is treated by the Green-function technique.
Group-theoretical selection rules are given for two-phonon infrared absorption and Raman scattering processes in crystals having the rocksalt structure. In common with the diamond structure, two-phonon overtones are infrared inactive. The selection rules for second-order infrared absorption processes in the rocksalt s…
Polarized absorption in the 5D2←7F0 transition and emission in the 5D0→7F2 transition of the Eu3+ ion have been obtained in monoclinic single crystals of the tetrahexylammonium salt of tetrakis diphenyl-propanedionoeuropium (III). Both sets of transitions consist of three lines, two polarizing strongly perpendicular t…
Lamellar compounds of graphite are often, but not always, deeply colored. To study this color, a number of different compounds have been prepared from very thin flakes cleaved from annealed single crystals. The spectral transmission of these samples has been measured between 0.2 μ and either 2.2 μ or, in a few cases,…
Results on dielectric polarization and its variations in strong electric fields are presented for solutions of hexanol-1 in hexane, benzene, 1,4-dioxane, and triethylamine. A method for calculating the dipole moments of multimers and complexes on the basis of experimental results is proposed. Also, the concentrations…
Powder x-ray-diffraction studies on tellurium up to 150 kbar show only two structural transitions at 40 and 70 kbar in agreement with Bridgman's work. The structure of the 40–70-kbar phase is unsolved. Above 70 kbar, it is proposed that tellurium is isomorphous with β-polonium and is rhombohedral with a=3.002±15 Å, α=…
Normal frequencies of crystalline polymethylene have been calculated for various phase differences along the c axis of the crystal. Intermolecular hydrogen—hydrogen force constants have been evaluated from the splitting of the spectroscopically active modes. The results of the calculations explain almost satisfactoril…
Abstract Morphology and kinetics of the spherulite crystallization has been studied for d,l ‐poly‐(propylene oxide) ( d,l ‐PPO) (M̄ n = 135,000) and l ‐PPO (M̄ n = 10,300). Both polymers have similar physical characteristics except that d,l ‐PPO normally gives non‐ringed spherulites whereas l ‐PPO exhibits the ringed…
The principal absorption bands induced by irradiation at liquid-helium temperature with x rays in CsBr crystals are the complex $F$ band and two overlapping $V$ bands at 435 and 497 m\ensuremath{\mu}. In view of the dichroic properties of these $V$ bands, the most obvious model seems to be a ${\mathrm{Br}}_{2}^{\ensur…
The thermoelectric power of Cu-Al and Cu-Si alloys has been determined from 4.2 to 320\ifmmode^\circ\else\textdegree\fi{}K. Assuming that the thermopower is separable into diffusion and phonon-drag components, the change in phonon-drag thermopower $\ensuremath{\Delta}{S}_{g}$ is determined for Cu+0.77 at.% Al and Cu+1…
The electronic band structure of ordered beta brass (${\ensuremath{\beta}}^{\ensuremath{'}}$ CuZn) has been calculated from first principles by the Green's-function technique. Two slightly different crystal potentials of the muffin-tin type have been tested, both based on free-atom Hartree-Fock wave functions. Each po…
The experimental results of phonon-drag thermoelectric power of $n$-InSb are analyzed to obtain information about electron-phonon and phonon-phonon interactions. We find that for temperatures greater than 6\ifmmode^\circ\else\textdegree\fi{}K, the piezoelectric mode of electron scattering is negligible as compared to…
The data of Allen and Gobeli on photoemissive yields from partially cesiated surfaces of several semiconductors with photon energies between 2 and 6 eV are analyzed in detail. The results are shown to be consistent with direct transitions in energy-band models obtained from semiempirical pseudopotentials based on inte…
An elementary analysis is given of the conditions for phase transformations of the first and second orders, in the molecular-field approximation. The analysis may be relevant to some ferroelectric, Jahn-Teller, order-disorder, and singlet-triplet transitions. On the assumptions of our two-level model, no transition ca…
X-ray diffraction powder patterns taken at high pressure suggest by analogy to Gd that Tb, Dy, and Ho have first-order transitions from a hcp to a Sm-type structure at high pressure. The $\frac{c}{a}$ ratio of the hcp phases increases with pressure toward the ideal value. The change of the Curie or N\'eel temperature…
Various kinds of clay minerals mixed with calcium carbonate and ammonium chloride were heated at a specific temperature in the range of 500-1000 degrees C. for one hour, and the reaction products were examined. The kinds of reaction products depend upon the chemical compositions of the clay minerals. In the case of cl…
Values of the enthalpy of dehydration determined by difierential thermal analysis are 151, 156 and 160 cal/gm for kaolinite, dickite and halloysite respectively. Activation energies for dehydration at a water pressure of 15 psi are consideratrly greater than published activation energies determined at much lower water…
The solubility of helium in uranium dioxide was calculated directly from atomic properties and compared with experiment. The calculations were based upon a statistical-mechanical formula which assumes dissolved helium to behave as a simple harmonic oscillator in an interstitial site in the UO2 lattice. Knowledge of th…