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The possibility of acoustic wave generation of nanometer range in plates is shown. The experimental results that show the possible reconfiguring of the generator frequency in YFeO3 with a constant magnetic field are given. [ABSTRACT FROM AUTHOR]

The liquid-vapor equilibria in the AsCl3-HCl-H2O system have been studied by a flow method at high hydrogen chloride concentrations (above 20 wt%) over the entire arsenic trichloride solubility range at temperatures from 25 to 105°C and a pressure of 1.013 MPa. The composition effects on the parameters of the liquid-vapor equilibria have been assessed, and the conditions for the most effective recovery of arsenic trichloride from hydrochloric acid solutions by distillation were established. [ABSTRACT FROM AUTHOR]

CuCr2S4-based solid solutions containing solute atoms on the Cu or Cr site were studied with the aim of changing the band structure of the spinel to semiconducting, while maintaining a high magnetic ordering temperature. Cu1 − xMxCr2S4 and CuCr2 − xMxS4 (M = Al, Ga, In, Fe, Co, As) quaternary phases were synthesized, and CuCr2S4, Cu0.3Co0.7Cr2S4, and Cu0.5Fe0.5Cr2S4 single crystals were prepared using high-temperature solution growth and chemical vapor transport. The magnetic materials were characterized by a variety of techniques. [ABSTRACT FROM AUTHOR]

The kinetics of degassing of industrial arsenic isolated from lewisite detoxification products was studied. The optimum conditions for the removal of gases and moisture were determined: the optimum procedure was found to be the treatment of industrial arsenic in a vacuum at 200°C for 1 h or in an inert atmosphere at 280°C for 1.5 h. Based on the theory of internal-diffusion desorption, a mathematical model of industrial arsenic degassing kinetics was proposed, which can predict, with high accuracy, the equilibrium and kinetics of desorption of gaseous components from powdered arsenic over given ranges of temperatures and starting concentrations of sorbed gases. [ABSTRACT FROM AUTHOR]

Systematic crystal-chemical studies of chalcogenide spinels and related phases are used to develop a novel, unified approach to analyzing the nonstoichiometry of close-packed phases in the series atacamite–spinel–halite with allowance for alternatively occupied tetrahedral and octahedral nonatacamite sites. The main physicochemical approaches to the synthesis and crystal growth of magnetic semiconducting chalcogenide spinels are considered. The phase diagrams of systems containing magnetic semiconducting phases are mapped out. To choose flux growth conditions, the liquidus relations in spinel–solvent systems and the kinetics of mass transport in chemical vapor transport systems are investigated. The influence of high temperatures and pressures on the structure of polycrystalline chalcogenide spinels is analyzed. The purity of the starting materials is shown to have a significant effect on the physical properties of chalcogenide spinels. Physical property measurements demonstrate that the magnetic semiconducting chalcogenide spinels have considerable potential for practical application. [ABSTRACT FROM AUTHOR]

Features of the photoluminescence spectra observed for various polarizations and intensities of the pumping radiation and the kinetics of photoluminescence of the CdS and CdSe nanocrystals grown in hollow nanochannels of an Al[sub 2]O[sub 3] matrix are explained in terms of exciton transitions in semiconducting quantum wires with dielectric barriers. The observed exciton transition energies coincide with the values calculated with an allowance for the effects of quantum confinement and the "dielectric enhancement" of excitons. The latter effect is manifested by a significant increase in the Coulomb attraction between electrons and holes (the exciton binding energy exceeds 100 meV) due to a difference between the permittivities of semiconductor and insulator. It is shown that the exciton transition energy remains constant when the quantum wire diameter varies within broad limits. This is related to the fact that a growth in the one-dimensional bandgap width of the quantum wire caused by a decrease in the diameter is compensated by an increase in the exciton binding energy. [ABSTRACT FROM AUTHOR]

The degassing kinetics of crude arsenic recovered from nonferrous waste was studied in air, vacuum, and flowing inert gas, and the degassing conditions were optimized. The sublimation of crude arsenic was carried out in vacuum and flowing hydrogen. A metallic arsenic compact was obtained, which is suitable for the synthesis of ultrapure arsenic compounds. [ABSTRACT FROM AUTHOR]

This work presents the calculation results of the Lamb wave spectra in a plate of iron borate. Experimental data on how flexural vibrations in a borate plate influence its domain structure are provided. [ABSTRACT FROM AUTHOR]

The characteristic features of the luminescence spectra of CdS semiconductor nanocrystals, crystallized in hollow channels in a dielectric template, are explained in terms of excitonic transitions in semiconductor–insulator quantum wires. The excitonic transition energies agree with the values calculated taking into account the effects of size quantization and the “dielectric enhancement of excitons” — the large increase in the electron–hole attraction as a result of the difference between the permittivities of the semiconductor and insulator. The theoretically computed binding energies of excitons in CdS quantum wires with a diameter of 10 nm reach 170 meV. It is shown that the excitonic transition energy is constant for a wide range of wire diameters. © 1999 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spectra of linear and nonlinear absorption of GaAs and CdSe semiconducting quantum wires crystallized in a transparent dielectric matrix (inside chrysotile-asbestos nanotubes) have been measured. Their features are interpreted in terms of excitonic transitions and filling of the exciton phase space in the quantum wires. The theoretical model presented here has allowed us to calculate the energies of excitonic transitions that are in qualitative agreement with experimental data. The calculated exciton binding energies in quantum wires are a factor of several tens higher than in bulk semiconductors. The cause of this increase in the exciton binding energy is not only the size quantization, but also the "dielectric enhancement," i.e., stronger attraction between electrons and holes owing to the large difference between permittivities of the semiconductor and dielectric matrix. [ABSTRACT FROM AUTHOR]

The author discusses several theories of history and argues for the concept of the progressive development of society. Vestnik Akademia Nauk (Bulletin of the Academy of Sciences), 1961, No. 4. Slightly abridged. [ABSTRACT FROM AUTHOR]