Effect of Pressure on Synthesis of Pr-Doped Zirconia Powders Produced by Microwave-Driven Hydrothermal Reaction

Abstract

A high-pressure microwave reactor was used to study the hydrothermal synthesis of zirconia powders doped with 1 mol%Pr. The synthesis was performed in the pressure range from 2 to 8 MPa corresponding to a temperature range from 215C∘to 305C∘. This technology permits a synthesis of nanopowders in short time not limited by thermal inertia of the vessel. Microwave heating permits to avoid contact of the reactants with heating elements, and is thus particularly well suited for synthesis of doped nanopowders in high purity conditions. A mixture ofZrO2particles with tetragonal and monoclinic crystalline phases, about 15 nm in size, was obtained. The p/T threshold of about 5-6 MPa/265–280C∘was necessary to obtain good quality of zirconia powder. A new method for quantitative description of grain-size distribution was applied, which is based on analysis of the fine structure of the X-ray diffraction line profiles. It permitted to follow separately the effect of synthesis conditions on the grain-size distribution of the monoclinic and tetragonal phases.