Evolution of aerosols in large pressurized spaces

Results of experiments in pressurized spaces of 100 to 3200 m³, including a manned space station, carried out to study the evolution of aerosols and ions in the course of their spontaneous decay and removal by an electric field or mechanical means are considered. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 844–850, July–August, 2000.     

Stabilization of New Phases in Ion-Conducting Nanocomposites

Physical properies of ion-conducting nanocomposites are reviewed. Special attention is paid to the change of the bulk characteristics of ionic salts in the nanocomposites due to the formation of the interface phases. The main thermodynamic reason of the formation of the nanocomposite as well as the stabilization of the interface phases is the adhesion energy _a. At sufficiently high _a values, the ionic salt tends to spread along the oxide surface, which leads to the formation of the nanocomposite on sintering. The adhesion is the result of the interface interaction and incorporates the stage of the specific adsorption of the interface ions. It leads to the formation of the double layer formed by the point defects in the interface region of the ionic salt. In the case of the strong adhesion, the structural reconstruction or the formation of the metastable interface phase takes place. Analysis of the experimental data shows that interface phases exist in composites AgI–Al₂O₃, MeNO₃–Al₂O₃ (Me = Li, Na, K, Rb, and Cs), CsHSO₄–SiO₂, RbNO₃–SiO₂ and CsCl–Al₂O₃. Their structure may be either epitaxial crystalline, or amorphous. The thickness of the interface phase as estimated on the basis of the brick-wall model is about 3–4 nm.     

Hydrodynamic Instability of Nonequilibrium Gas in the Region of Thermal Explosion

The convective instability of a flat layer of a nonequilibrium gas is investigated under different conditions of energy pumping. The conditions under which convective, thermal, and acoustic instabilities arise are compared, and the regions of thermodynamic parameters at which a specific type of instability is dominant are determined. The effect of boundary conditions and of vibrational thermal conductivity (diffusion of vibrational quanta) on the convective instability of a system in the region of thermal explosion is revealed.     

Structure and catalytic properties of samarium-calcium oxide catalysts in methane oxidative dehydrodimerization

Synthesis of samarium-calcium oxide catalysts has been studied. Conditions for obtaining systems that contain cubic, monoclinic and mixture of two forms of samarium oxide have been found. The catalyst with two Sm₂O₃ forms has been shown to be the most active and selective towards oxidative dehydrodimerization of methane. Electrical conductivity over samarium-calcium catalysts have been studied. It is concluded that high selectivity and activity of the samples with two Sm₂O₃ forms are due to high mobility of oxygen vacancies.