Materials Literature
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Two different forms have been proposed for the relation between the frequency-dependent dielectric constant of a polar substance and the autocorrelation function for the net dipole moment of a small spherical region inside the dielectric. We find that one of them is correct, while the other one describes a spherical s…
Molecular dynamics calculations have been carried out on the singlet distribution function (sdf) in hard-disk and hard-sphere solids. The dependence of the distribution function upon particle number and density and the deviations of this function from spherical symmetry are examined. The possible connection between th…
A Raman study of ferric chloride hexadydrate (FCHH) in 11.5M HCl solutions has shown the presence of tetrahedral FeCl4− ion as the most prominent species. An appreciable concentration of a polymeric species, which is composed of higher chloroferrate groups of the type FeCl5 · H2O, and a small concentration of lower ch…
Switching phenomenon in amorphous semiconductors is analyzed in an electrothermal model. Current-voltage characteristics are obtained from very general mathematical considerations concerning existence, uniquencess, local and global stability, and bifurcation of solutions of the nonlinear equations for temperatures and…
The ionization potentials of the gaseous atoms, monoxides, and dioxides over the refractory oxides of Ti, Zr, Hf, Th, U, Y, and La have been obtained from ionization efficiency curves and appearance potentials by electron impact. A method of simultaneous and intercomparative measurements with known standards was used.…
A study of the room-temperature infrared reflectance and Raman spectra has been made on a ${\mathrm{Ge}}_{0.30}$${\mathrm{S}}_{0.70}$ glass. The dominant features of the two spectra are complementary with respect to frequency, and can be understood in terms of a molecular model in which the Ge atoms are fourfold coord…
The heterogeneous oxidation of CO on epitaxially grown Pt(111) surfaces has been investigated using modulated molecular beam techniques. Within the range of pressures from 10−7 to 10−5 torr and temperatures from 450 to 950°K, the overall reaction is apparently first order. The observance of higher order kinetics in th…
The dispersion of the third order optical nonlinear polarizabilities of benzene, chlorobenzene, and nitrobenzene is measured in the vicinity of Raman active vibrations. Observation of interference between resonant and nonresonant contributions determines the magnitude and phase of the electronic hyperpolarizability. S…
Fine structure in the energy distribution of secondary electrons "back-scattered" from a graphite crystal surface is resolved and shown to be consequence of inelastic electron-electron scattering in which the dominant process is the population of final states above the vacuum level by electron-hole pair production via…
The ferroelectric phase transition in SnTe from a cubic to a rhombohedral structure at liquid-helium temperatures is investigated by Raman-scattering techniques. Using a backscattering geometry, Raman peaks are observed which correspond to $q\ensuremath{\simeq}0$ longitudinal-optical (LO) phonons in bulk $p=2.2\ifmmod…
The superconducting phase transition is predicted to be weakly first order, because of effects of the intrinsic fluctuating magnetic field, according to a Wilson-Fisher $\ensuremath{\epsilon}$-expansion analysis, as well as a generalized mean-field calculation appropriate to a type-I superconductor. Similar results ho…
Simple perturbation theory predicts that the lattice thermal conductivity should be inversely proportional to the absolute temperature. It is shown that the lattice thermal conductivity of minerals should not depart markedly from that variation, even when the average phonon mean free path is comparable to the lattice…
Ordered protodolomite, CaMg(CO(3))(2), has been synthesized at 100 degrees C by reaction of metastable precipitated carbonates with aqueous magnesium-bearing solutions. Initial reaction products have expanded crystallographic cells, attributed to the presence of structural water. Longer reaction time produces a protod…
It is shown that attractive electron-electron interaction arising from the exchange of two optical phonons is a possible mechanism for superconductivity in some degenerate semiconductors. This mechanism is present independent of whether the semiconductor is many-valley or not. Application to SrTi${\mathrm{O}}_{3}$ is…
MOLYBDENUM wire, as a coating material, is well known since molybdenum has many advantages as a hard bearing surface; it is highly scuff‐resistant and has a low coefficient of friction. Metco now announce a self‐fusing, high‐molybdenum powder which can be plasma flame sprayed to produce tough, wear‐resistant coatings…
An analytical study of the operation of electret transducers subject to relative displacements of the electrodes comparable to the thickness of the air gap (or air gaps) between electret and electrodes is presented. In particular, the relations between generated voltage and time history of the transducer capacitance a…
Assuming the atomic motions in water, methanol and ethanol as similar to those of solids, the effective Debye temperature has been calculated as a function of temperature and pressure for these liquids.
The study of the chemistry of so-called conventional photography, based on the photosensitivity of silver halides, has been a part of chemical research for nearly 150 years, yet it still has many unanswered questions to deal with.
Abstract The complex carbonates of iron(III) are shown to be anionic in nature. The solutions containing these complexes show a maximum absorbance at 460 nm. The complex carbonates of iron(III), viz., (i) K 6 [Fe 2 (OH) 2 (CO 3 ) 5 ] · H 2 O, — (ii) Na 2 [Fe 3 O 2 (OH) 3 (CO 3 ) 2 ], — (iii) K[Co(NH 3 ) 6 ] 2 [Fe 3 (O…
Diffusion treatments may comprise the diffusion of interstitial elements such as oxygen, nitrogen, carbon, or boron into the surface from a gaseous or molten salt bath environment, or less commonly it may consist of substitutional diffusion of a previously deposited metal coating or by packing in materials such as fer…