Materials Literature
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In this paper, Dingle's theory of the screening of impurity ions in semiconductors is generalized. This is accomplished by inserting in the theory of screening the spatial dielectric function of the medium. Poisson's equation for the potential of an impurity ion follows from one of Maxwell's equations. With the analyt…
Lattice defects in a metal modify the conduction-band carrier density at the defect site. Thus transport, past the scattering caused by thermal lattice vibrations, becomes easier (or harder) in the region of changed carrier density. The resulting transport field inhomogeneities have been discussed in earlier work on e…
The temperature dependence and magnitudes of the reciprocal decay length ${l}^{\ensuremath{-}1}$ of low-intensity longitudinal and transverse phonon pulses propagating in fused silica glass between 0.02 and 0.5 K for frequencies near 0.5 GHz are reported. The temperature dependence of ${l}^{\ensuremath{-}1}$ is in goo…
A nonlocal theory for the surface photoeffect produced in metals by vacuum ultraviolet radiation is presented. Using a simple electron-gas model, it is shown that $p$-polarized incident light generates, in the surface region, a strongly spatially dependent vector potential having longitudinal character; it is argued t…
The energy-level spacings for electrons and holes in surface-charge layers on Si(100) are determined from a measurement of direct optical absorption of far-infrared laser radiation guided along the surface. At photon energies in the range 5.64-15.81 meV, the separation of the electric subbands is measured as a functio…
The physical properties of $4Hb\ensuremath{-}\mathrm{Ta}{\mathrm{Se}}_{2}$ suggest the development of two charge-density waves (CDWs) of different symmetry. Electron and neutron diffraction studies establish that layers with octahedral and trigonal prismatic (TP) coordination undergo independent transitions to CDW sta…
A nonempirical localized-orbital approach is used to calculate the electronic structure of ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$, ${\mathrm{As}}_{4}$${\mathrm{S}}_{4}$, ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$, ${\mathrm{As}}_{4}$${\mathrm{Se}}_{4}$, and ${\mathrm{As}}_{2}$${\mathrm{Te}}_{3}$ crystals. Contributions of…
Some applications of molecular dynamics calculations to the vitreous state have been examined for simple ionic MX and MX2 type glasses. The MX system which corresponds to a hypothetical vitreous and supercooled amorphous KCl is found to undergo an isobaric transition in the region of 0.3 Tf and an isothermal transitio…
The lowest-energy state of the incommensurate charge density wave (CDW) near the lock-in transition is found to be a distorted plane wave. An exact solution is found in the weak-coupling limit and the lock-in phase transition is continuous. A new defect is found in the commensurate CDW, a discommensuration, in which t…
We have measured the melting temperatures of crystallized suspensions of polystyrene spheres as a function of concentration. By analyzing the data on the basis of a simple model we can estimate the heat of melting and the entropy change.
The Compton scattering of circularly polarized $\ensuremath{\gamma}$ rays was used for studying the linear momentum distribution of electrons with unpaired spins in ferromagnetic iron metal. The observed Compton profile shows a broad minimum around zero momentum. The results are discussed in comparison with those calc…
The resolution and field of view attainable in electron microscopes is limited by third-order aberrations of the optical system. While considerable effort has been made to determine the effects of these aberrations on the CTEM, little work has been done for the case of the STEM, We have found that one of the advantage…
Report describes effectiveness and materials compatibility of amine nitrites. Particularly of value to those interested in long-term corrosion protection.
A STEM which includes a corrector for primary spherical aberration has been built and is being put into1operation. The microscope is expected to achieve a resolution of 1 Å at 50 keV. This high resolution is possible because of the correction of spherical aberration. The corrector and its operation have been described…
Abstract Exciton fine structure is measured in hexagonal AgI by two‐photon absorption. A detailed assignment of the different P‐exciton states is possible using the appropriate polarization configurations. The experimental results can be explained quantitatively taking into account anisotropy as the only perturbation…
Thirteen alpha, omega-alkanedicarboxylic acids (C2-C12, C14, and C16) and their dimethyl esters were tested against Aspergillus niger, Trichoderma viride, and Myrothecium verrucaria in Sabourauc dextrose agar at pH 4.0 AND 5.6. Toxicity to Canadida albicans, Trichophyton mentagrophytes, and Mucor mucedo was determined…
The motion and location of the molten clad during an unprotected loss-of-flow accident in liquid-metal fast breeder reactors are very important because of their effect on the reactivity and the subsequent fuel motion. The present study analyzes the clad relocation problem based on a single-channel film flow model and…
Abstract Enthalpies of formation h 1 of Ge Te alloys were measured by direct reaction calorimetry in the temperature range 1030 < T /K < 1150 and at mole fractions 0.25 < x Ge < 1. The measurements were performed with a high temperature ( T /K < 1400) Tian‐Calvet calorimeter. When referred to liquid te…
Abstract The absorption and reflection coefficients of GeSe single crystals are measured at various temperatures in the spectral range 0.8 to 2.2 μm using linearly polarised light. The main absorption mechanism is due to indirect interband electronic transitions with participation of two different phonons. Indirect en…
An atomic oxygen beam and mass spectrometer were used to measure the oxygen atom reflection γ16, recombination γ32, general surface reaction γM, and occlusion γ0 probabilities on six different engineering surfaces as a function of atomic oxygen exposure. The materials studied include gold, Nichrome V, aluminum, titani…