ИСТИНА

In the report are given the results of investigations of kinetics and mechanism of synthesis of simple and composite fine-crystalline oxides from solid-phase precursors in suband supercritical water fluid (SCWF). It was shown that processes of transformation and formation of new phases flow past more intensively in medium of water vapor. The rate of processes strongly depends on pressure of water vapor. It was ascertained that water molecules of fluid actively participate in processes of transformation of precursors. X-ray analysis, mass-spectrometry and IR-spectrometry of products obtained during synthesis in water fluid reveal existence of intermediate solid phase hydrated at the initial stages of reaction. The synthesis of quartz and corundum and in SCWF transits through a stage of formation hydrated intermediates. The basic type of crystals defects synthesized in SCWF represents oxygen vacancies incipient during dehydroxylation of an intermediate structure at formation final product. Changing state of a water fluid (P, T) it is possible to influence on local processes of crystals build-up and to produce crystals with various size, habitus and degree of perfection.