Specific features of the crystal and local structures of compounds formed in the Dy2O3–HfO2 system

Abstract

The crystal and local structures of compounds formed in the Dy2O3–HfO2 system (at molar ratios from 1: 3 to 3: 1) in the course of isothermal annealing of X-ray amorphous mixed hydroxides at temperatures up to 1600°C have been studied. At the molar ratio Dy2O3: HfO2 from 1: 3 to 1: 1, crystallization leads to formation of single-phase defect fluorite solid solutions nDy2O3 ∙ mHfO2 with clearly pronounced nonequivalence of parameters of local environment of Dy3+ and Hf4+ cations. It has been found that Dy2H2O7 (Dy2O3: HfO2 = 1: 2) samples have a tendency to pyrochlore-type ordering in both the cationic and anionic sublattices.