Modeling of the Mechanism of Phase Transitions in ZrO2 with Small Additions of In2O3 at High Temperatures in a Vacuum

Abstract

In the work were considered the models and analytical study crystallographic sequence of the phase transition in zirconium dioxide at heated. It has been shown, that mechanism of the transformation of monoclinic phase in tetragonal modification takes place at a move of two atoms of oxygen from of three in positions of the structure. At that a move is form a nodal anion vacancies, which are elements of the structure. The accumulation of such vacancies and the appearance of new anion vacancies, which form at evaporation of the oxygen from the lattice zirconium dioxide lead to the appearance zirconium cations of different valence. The transformations of phase of zirconium dioxide upon heating had : tetragonal – cubic, type C - cubic, type F, occur by shifting of the certain concentrations of anion vacancies in the non-structural position. The sequence of phase confirmed experimentally by heating in the temperature range 25 -1600oC in vacuum, samples of zirconium dioxide with addition 5 mol.% In2O3, prepared with hot pressure. The existence in nature is of compounds Zr2O3, with a cubic modification type C – pyrochlore, theoretically and experimentally confirmed.