Modern methods for hydrothermal synthesis of ZrO2-based nanocrystalline powders

Abstract

Hydrothermal decomposition, hydrothermal crystallization, hydrothermal homogeneous precipitation, microwave hydrothermal synthesis, ultrasonic-assisted hydrothermal synthesis, hydrothermal synthesis under supercritical conditions, which are used to produce ZrO2-based nanocrystalline powders, are considered. It is established that the nucleation and particle growth can be controlled in hydrothermal synthesis (through concentration change, increase or decrease in hydrolysis temperature, increase in hydrolysis time, introduction of surface active agents during dehydration, pH change during removal of admixtures, etc.) and thus high-pure homogenous powders with particles of different shapes can be produced in these conditions. They do not require additional grinding or thermal treatment at high temperatures, which usually involves the pollution of powders and decreases their activity in sintering. It is shown that the powders are used to produce transformation-hardened ceramics, catalyst supports, thick films, oxygen sensors, materials for solid oxide fuel cells (SOFC), electrochemical oxygen pumps, thermal-barrier coatings, and bioinert implants.