Materials Literature
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It is shown that the high-temperature behavior of the lattice thermal conductivity of silicon, which has been carefully remeasured recently by Fulkerson et al., can be explained by the four-phonon processes. It has been also found that the major contribution to the phonon thermal conductivity at high temperatures come…
Callaway's model of lattice thermal conductivity has been modified by introducing an arbitrary relation between the phonon frequency and the phonon wave vector, to take account of (i) the phonon dispersion, and (ii) the number of phonon states in the wave-vector space, allowing for separate contributions of the transv…
Measurements on thin films and surfaces have generated a need for a technique whereby one can calculate the phonon properties of small particles containing only a few hundred atoms. We have used moleculardynamic techniques to calculate the frequency distribution and various moments for five different particle configur…
The soft-mode damping and the ultrasonic attenuation at a displacive phase transition has been calculated with the help of a model Hamiltonian. The soft-mode damping parameter $\ensuremath{\Gamma}$ is finite at the transition temperature, whereas the ultrasonic attenuation $\ensuremath{\alpha}$ is singular. For sound…
The single-crystal electron spin resonance spectra of (VII), Mn(II), and Ni(II) are reported in the diamagnetic lattice CsMgCl3 at 298 and 77°K. The structure of the host lattice CsMgCl3 is also reported. The crystal system is hexagonal, space group P63/m mc. The basic structural feature is the linear array of [MgCl6]…
New photoemission data have been obtained from evaporated films of gold in the range of photon energies between 5 and 21.2 eV. With the exception of a single direct transition, all the optical transitions appear to fit a nondirect model; consequently, it has been possible to construct an optical density of states (ODS…
The nonlinear optical properties of Ag3SbS3 (pyrargyrite) as determined by second harmonic generation (SHG) with the 10.6μ CO2 laser are presented. Phase-matched nonlinear mixing is possible and the material is suitable as a phase-matched standard in the infrared for optical nonlinearities.
Beam-attenuation measurements were made on free-standing polycrystalline films of various thicknesses at energies between the work function and several electron volts above. The electron-electron collision mean free paths ${l}_{e}$ were determined by correction of the attenuation lengths for electron-phonon scattering…
The self-consistent phonon theory of anharmonic lattice dynamics is derived via a stationary functional formulation. The crystal dynamics is approximated by a set of damped oscillators, and these are used to construct a trial action, analytically continued into the complex time-temperature plane. Using the action, a f…
Recently, Nozi\`eres et al. have shown that Mahan's model x-ray problem (coupling between the deep hole and electron-hole excitations) could be solved exactly for the singular exponents. Here, it is shown that Lundqvist's model x-ray probelm (coupling between the deep hole and plasmons) may also be solved exactly. Fur…
Abstract This paper considers a multi-phase chemical system which includes solid substances, which can sustain non-hydrostatic stresses. The correct mechanical coordinates are introduced for a phase, which give the correct work done whether the dimensions of the phase are altered by deformation, phase transformations,…
Evidence for the decay of surface plasmons into one-electron excitations has been obtained in photoemission measurements from a slightly roughened surface of aluminum. A simple theory has been developed which explains the resultant photoyield in terms of both the drop in reflectance resulting from roughness-aided plas…
A basic thermodynamic cycle for the production of mechanical power from materials that may be made to contract forcibly and reversibly is described. The cycle differs from existing mechanical power cycles which generally employ expanding fluid as working substances. A "contraction turbine" operating on this cycle has…
Failure under dynamic compression of ductile tungsten alloys was examined by conducting symmetric Taylor tests at impacted speeds ranging from 200 to 350 m/s. A fracture parameter consisting of the average surface shear crack length was identified and computed as a function of the impact velocity. From these data, a t…
On October 5, 1966, during a slow increase in power, the Enrico Fermi Reactor was shut down in an orderly manner after it was obseryed that the control rods were withdrawn further than normal for 31MWt, that several subassemblies had abnormally high outlet temperatures, and that a small amount of F.P. was detected by…
Systematic approaches on the material selection for rickshaw frames were applied by cost per unit and weighted property method using modified digital logic. Ashby's material selection charts were used for preliminary material selection and relative cost analysis. Physical and mechanical properties and the main failure…
Effects of precipitation phases on the mechanical properties at room temperature and on the creep rupture strength at 800°C of 25Cr-20Ni heat-resistant cast steel containing carbonranging from 0.06 to 0.4% were investigated. The results obtained were summarized as follows:(1) With increasing the aging time at 800°C, m…
In order to obtain the knowledge of the bond energy relations in alkali silicate glasses and crystals, a series of thermochemical calculations was carried out.The experimental data used for the calculation were the previously reported values of the heat of solution of silicates in high alkali region and the present va…
Caking mechanism of common salt was studied from a behavior of a small amount of liquid on the surface of the salt crystals and following results were obtained.1. The caking is an attachment of salt crystals either by pressure or by recrystallization. The caking of the salt in a warehouse is attributed to the atter.2.…
Seven iron-silicon alloys having various silicon contents up to about 14% were polarized in 2 N H2SO4. The relationship between silicon contents in the alloys and various properties such as the maximum or the limitting current density and the passive potential and the passive current density were investigated. 14% sil…