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Xerogels and powders of a solid solution based on zirconium dioxide are synthesized by the method of coprecipitation of hydroxides from aqueous solutions of salts of zirconium nitrate ZrO(NO3)2⋅2H2O, aluminum Al(NO3)3⋅9H2O, and cerium Ce(NO3)3⋅9H2O with an aqueous 1 M solution of ammonia NH4OH. A dense ceramic with low porosity and water absorption is obtained. The effect of the ultrasonic treatment of the precipitate and mechanical treatment of the xerogel on the physicochemical properties of the obtained materials is evaluated. [ABSTRACT FROM AUTHOR]

By using the method of coprecipitation of hydroxides in the ZrO2–CaO–MgO system, xerogels, powders, and ceramics based on them are obtained. The effect of low temperatures during the preparation of precursors on the phase composition and physicochemical properties of the materials is studied. It is shown that the use of precipitate's cryotreatment makes it possible to reduce the open porosity and water absorption of the ceramics. [ABSTRACT FROM AUTHOR]

This article describes the production of nanodisperse xerogel and powders (average CSR size of 9 nm) in the ZrO2–Y2O3–Al2O3 system by coprecipitation of hydroxides. A strong highly porous ceramic has been produced from the initial powder with the composition of [(ZrO2)0.97(Y2O3)0.03]0.8(Al2O3)0.2 with pore forming additives using patented solid phase sintering. Using Doppler sonography, the volume of blood flow in arteriolas and capillaries has been estimated 150 and 250 days after implantation of plates. Therefore, the microcirculatory Doppler sonography seems to be a promising intravital method of estimating blood flow in the zone of plates from biocompatible nonresorbable material and, probably, inside the plates. It has been found that the ceramic plates based on zirconium dioxide in the body of experimental animals do not result in a negative reaction of animal's body. The in vivo experimental results make it possible to state that the obtained bioceramic based on zirconium dioxide is a promising material for endoprosthetics. [ABSTRACT FROM AUTHOR]

Mesoporous nanosized aerogels, xerogels, and powders in the ZrO2–Y2O3–CeO2 and ZrO2‒Y2O3–Al2O3 systems have been obtained by liquid-phase synthesis methods. The thermolysis, phase composition, and textural features of the synthesized materials have been studied. It has been found that the predominance of Lewis acid sites (LASs) on the surface of their particles indicates its lower hydroxylation and, as a consequence, a lower degree of agglomeration of the obtained materials. [ABSTRACT FROM AUTHOR]

Nanocrystalline ceramic samples of the ZrO2–3 mol % Y2O3 composition with varying degrees of tetragonality c/a (1.4337 and 1.0425) are obtained. The process of the low-temperature degradation of ceramics is studied by the methods of X-ray phase analysis and electron microscopy. It is found that samples with a high degree of tetragonality are more resistant to the action of a humid environment, while the phase composition in the bulk of the samples remains practically unchanged and the transformation t-ZrO2 → m-ZrO2 occurs mainly in the surface layers without significantly affecting the mechanical properties of the ceramics. [ABSTRACT FROM AUTHOR]

A strong highly porous ceramic for endoprosthesis possessing open porosity and elasticity modulus values similar to those of bone tissue is prepared through the solid-phase sintering of specimens of the initial powders of the (ZrO2)0.97(Y2O3)0.03 and [(ZrO2)0.97(Y2O3)0.03]0.8(Al2O3)0.2 compositions with blowing agents. The dependence of the characteristics of the sintered ceramics on the composition of zirconium-containing powders and blowing agents is investigated. [ABSTRACT FROM AUTHOR]

The results of the studies of the conditions of the liquid-phase synthesis of highly dispersed xerogels with a low degree of agglomeration and precursor nanopowders (~10-12 nm) based on zirconium dioxide in the ZrO-HfO-YO(CeO) system are presented. The thermal decomposition of xerogels and formation of crystalline solid solutions with the structure of fluorite are investigated. The optimal conditions for the solidification of nanodispersed powders for fabricating compact ceramics based on solid solutions of ZrO and the physical-chemical properties of these ceramics are studied. [ABSTRACT FROM AUTHOR]

The technology of liquid-phase synthesis of mesoporous xerogels and aerogels based on ZrO-YO-CeO is developed. Xerogels are obtained by the coprecipitation of hydroxides, while aerogels are obtained in accordance with the sol-gel technology: the average pore size is 1.5-17.2 nm and the specific surface area is 120-878 m/g. Aerogels are characterized by a high degree of porosity: the pore volume attains 1-4 cm/g. Based on precursor xerogels, nanopowders of a tetragonal solid solution of the (ZrО)(YО)(CeО) composition with a particle size of 5-9 nm and S = 74 m/g were fabricated. Due to the high values of their specific surface area, the synthesized xerogels and aerogels are promising as sorbents, catalysts, or catalyst supports. [ABSTRACT FROM AUTHOR]

By using the method of coprecipitation of hydroxides in the ZrO2–CaO–MgO system, xerogels, powders, and ceramics based on them are obtained. The effect of low temperatures during the preparation of precursors on the phase composition and physicochemical properties of the materials is studied. It is shown that the use of precipitate's cryotreatment makes it possible to reduce the open porosity and water absorption of the ceramics. [ABSTRACT FROM AUTHOR]