Oleinik O. Synthesis and research of properties of nanocrystalline ceramics with semiconductor-metal phase transition

The subject of the thesis is developing the technology of obtaining nanocrystalline ceramics with a phase transition semiconductor-metal. The technique involved allows obtaining the nanocrystalline vanadium-phosphatic glass-ceramics that possesses the improved physical and mechanical properties, that predetermines expediency of its use as the material for making critical thermo-resistors and electric switches. Thermodynamic study of equilibrium composition of the systems V-О-Н-Na and V-O-H-S as water solutions was carried out in order to study conditions of the process. Initial component composition and temperature of the process necessary for obtaining nanocrystalline vanadium dioxide were determined. Conditions at which steady sol of nano oxavanadium particles exists were found. Obtaining VO2 in two stages from ammonium vanadite with subsequent thermotreatment was experimentally proved. Influence of technological parameters for glass-ceramics obtaining on its physical and mechanical properties is studied. The tests of critical thermo-resistors and electric switches made of nanocrystalline vanadium-phosphatic glass-ceramics showed improved properties.