Nanocrystalline Powders of Dysprosium Hafnate and Ceramics on Their Basis

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.