VOL 76, No. 10 (2003)

The first nonlinear optical nanocomposite based on a fusible glassy matrix and a ferroelectric crystal has been obtained. Lead-borate glasses were used as a matrix, and a single-phase ferroelectric powder KNbSi ₂ O ₇ served as a filler. The quadratic optical nonlinearity of composites has been studied as a function of the temperature and duration of dissolution of crystals in a glass matrix. The conditions for obtaining transparent nanocomposites generating the second optical harmonic are determined. Tab. 1, ill. 3, bibliography: 14 titles.

The sol-gel method synthesized phosphors based on strontium aluminates activated with europium and dysprosium ions. The effect of the ratio of strontium and aluminum oxides on the crystallization and luminescent properties of the obtained luminophores has been investigated. It is shown that the dispersion of luminophore powders is 3 - 4 microns. In this case, in contrast to the traditional method of solid-phase sintering, the stage of grinding materials can be excluded. Tab. 1, ill. 4, bibliography: 13 titles.

The basics of making foam glass are considered. The relationship between the structure and properties of the resulting material, such as density, water absorption, strength and thermal conductivity, is shown. The advantages, disadvantages and prospects for the development of one of the "cold" methods of producing foam glass are reflected.

The main trends in the development of a wide range of bioactive medical materials based on glasses are considered. They are classified according to their composition, physicochemical properties and in relation to body tissues. Tab. 2, ill. 3, bibliography: 31 titles.

The fundamentals of obtaining highly dispersed powders of oxide materials, including those of complex composition, by the sol-gel method are considered. Various compounds (polyacrylic acid, polyacrylamide, polyvinyl alcohol) were used as a gelling agent in true and colloidal solutions of the main components. When obtaining powders by the sol-gel method, the temperature of synthesis of complex compounds is reduced by 150 - 200 ° C, while the particles are nano-sized. Tab. 5, ill. 1, bibliography: 11 titles.

The processes accompanying the creep of ceramics and refractories are considered. Structural defects according to their effect on creep can be arranged in a row (in order of decreasing impact): macropores; inclusion of low-melting phases, especially the glass phase; micropores; crystal boundaries, especially those passing through micropores; block boundaries; dislocation; vacancies. The sequence in the series is determined by the intensity of diffusion mass transfer, i.e., by the concentration of vacancies near the listed structural elements (defects). Il. 8, bibliography: 22 titles.

The results of a study of the effect of Y ₂ O ₃ and CaO additives introduced into the charge in the form of oxides and salts on the sintering and properties of ceramics based on AlN are presented. The effect of high-temperature annealing of ceramics in a flow of a mixture of nitrogen and hydrogen on its properties is shown. Tab. 1, ill. 1, bibliography: 1 titles.

The additives used in the technology of corundum ceramics, which form a liquid phase during the firing process, are classified. The basic principles are formulated that must be taken into account when choosing additives that ensure the production of high-quality alumina materials with a low sintering temperature. A number of eutectic systems have been proposed, the introduction of which into corundum allows the production of dense ceramic materials at firing temperatures of 1350 - 1550 ° C. Some features of the sintering of these materials are considered. Tab. 2, bibliography: 14 titles.

The results of the influence of some oxides on the sintering and properties of ZnO ceramics are presented. The introduction of additives from solutions of the corresponding salts has a better effect on the formation of the ceramic microstructure. In this case, ceramics are actively sintered according to the liquid-phase mechanism in the presence of glass-forming Bi ₂ O ₃ and Sb ₂ O ₃ and Ni oxides , Mn, Sn, etc. Il. 3, bibliography: 5 titles.

The structures of materials with various matrices based on silicates with additions of wollastonite as a filler are considered. The dependences of strength and other properties on the amount of introduced wollastonite and its characteristics are analyzed. Tab. 2, ill. 5, bibliography: 6 titles.

When the detonation products of C ₄ H ₄ N ₈ O ₁₄ interact with copper, tenorite and a previously unknown modification of cuprite with face-centered cubic lattice with a = 12.078 E. X-ray diffraction data of the detected copper oxides are presented. Tab. 2, ill. 2, bibliography: 11 titles.