Nanocrystalline Powders of Dysprosium Hafnate and Ceramics on Their Basis

Abstract

Chemical deposition from salt solutions (co-deposition) has been chosen and investigated as a method for synthesizing dysprosium hafnate complex oxide Dy₂HfO₅. Regimes for synthesis of low-aggregated single-phase Dy₂HfO₅ nanocrystalline powders using a microwave furnace have been developed. It is shown that the synthesized Dy₂HfO₅ powders subjected to high-energy grinding and mechanical activation consist of crystallites with a size of no larger than 10 nm and a specific surface of no smaller than10 m²/g. High-density ceramics has been prepared by uniaxial compacting of mechanically activated nanocrystalline powders with subsequent isothermal annealing of the compacts. Test batches of the Dy₂HfO₅ pellets with a density ranging from 8.25 to 9.10 g/cm³, a thermal conductivity varying from 1.21 to 1.63 W/(m K), a thermal expansion coefficient in the range from 7.1 to 8.7 × 10^–6 K^–1, and Young’s modulus in the range from 168 to 221 GPa have been fabricated and certified.