The aim of present study was the investigation of purification efficiency of industrial white fused alumina at high-temperature calcinations, in vacuum. Three powder samples of alumina with different initial purity and particle size distribution were studied. The impurities amount in the white fused alumina powder decreased by factor 10 after vacuum calcinations. White fused alumina samples were almost completely cleared of Na, Mg, K, Mn, Cu and Zn. The iron content in the studied samples decreased by factor 8–10. Comparison of the granulometric composition and specific surface area of samples, showed that samples look like sets of porous grains with the average sizes between 16–60 μm. In turn, porous grains are composed of dense micro-particles with a characteristic size of 0.4–0.7 μm. The specific surface area of grains lies in the range 2.8–3.3 cm2/g. Relatively high rate of purification takes place due to porous structure and high surface area of the samples.

The experiments were carried out to show that it was possible to raise the chemical purity of the electrically fused alumina powders by means of the high-temperature (about 1750 °C) vacuum (about 10–5 mm Hg) roasting. Three samples of the commercial fused corundum were heat-treated, the samples having different size grading and impurity composition, after the treatment the impurity level turned out to be ten times as less: the samples were almost completely cleared off Na, Mg, K, Mn, Cu and Zn impurities, the iron content decreased by the factor of 8‒10. It was determined that the samples were built up of the porous pellets of the size of 16‒60 microns, formed out of the solid micro-particles of the size of 0,4‒0,7 microns. The pellets' specific surface area was within the 2,8 and 3,3 cm/gram.

A method for the determination of trace impurities of tens of ppm in solid materials is proposed, based on laser-induced evaporation of the substance in a vacuum in the forced congruence mode with simultaneous analysis of the evaporation products using a time-of-flight mass spectrometer. The results of measurements of the relative composition of impurities in α-corundum obtained from aluminum hydroxide (AlOOH) powder by high-temperature annealing (1500 and 1800°C) are presented. The necessity of comparative analysis is caused by a substantial difference in the measurement results for impurities in the initial material obtained by conventional methods. The reported values of the relative composition of impurities are in a good agreement with the results of inductively coupled plasma mass spectrometry.

An experimental setup developed in cooperation between the Institute for Energy Problems of Chemical Physics and the Joint Institute for High Temperatures for studying processes that occur during laser sublimation and for modeling thermophysical and chemical processes in situ at high temperatures in large-scale facilities is described.

Forms of the condensed phase created under the action of a high-power CO2 laser pulse (power, 4 J/pulse; λ = 10.6 μm; pulse duration, 1.5 μs) on optical sapphire (Al2O3) solid targets are investigated. The ablation products emitted from the laser crater and the particles formed in the space above the surface of the target are collected using witness samples oriented in a predetermined manner with respect to the laser crater. Forms of the condensed phase are studied via electron microscopy and atomic force microscopy. Conclusions are drawn as to the mechanisms of formation of particles with different shapes and structures, including Al2O3 vacuum hollow microspheres (hollow bubbles).

This work presents the results of experimental study of hydrodynamic and thermal characteristics of a plume of suboxide AlO, produced by interaction of intensive irradiation of a pulsed CO2 laser with a target material. The space-time distributions of vibrational temperatures of AlO molecules were obtained.

An experimental facility for studying the kinetics of molecular association formation from atoms produced by evaporation of the target material by powerful CO 2 laser pulses is described. First experimental results are presented for the spectral and spatial-temporal characteristics of the spread of Al atoms produced in interactions of laser radiation with aluminum oxide Al 2 O 3 , followed by AlO formation in various low-pressure (0.1–0.3 Torr) atmospheres. Images of structurally similar forms condensed on a glass surface have been observed with an atomic-force microscope.

The internal friction method in the free oscillation mode was used to study the temperature dependences of the dissipation loss spectra and shear modulus in a Pd polycrystalline system, PdH0.5 interstitial solid solution, and dehydrogenated Pd system. It is found in the studies of spectra and shear modulus that full hydrogen desorption from a- and b-phases of the PhH0.5 system occurs after the first heating cycle of the system. The dehydrogenated system, like the initial system, features the same number of peaks in the internal friction spectrum in the temperature range of 50–150×C. The temperature dependences of the shear modulus of the initial and dehydrogenated systems coincide. The presence of dissipative processes in the solid solution is related to mobility of hydrogen atoms in a FCC structure of Pd and causes a modulus defect in the temperature range of appearance of loss peaks in the spectrum. The possibility of describing the modulus defect within the phenomenological models in the inelasticity theory is considered.

The temperature dependences of dissipative loss spectra were studied by the internal friction method for the polycrystalline Pd system and interstitial solid solutions PdH x . Four relaxation processes related to the structural peculiarities of the crystal lattice were observed in Pd; two additional relaxation processes were observed in PdH x solid solutions. The latter were related to the mobility of hydrogen atoms in different phases of the face-centered cubic crystal structure.