Stabilization of Polymorph Phases in Oxides. Polymorph Transformations

Abstract — Polymorphic transitions in oxides controlled by diffusion proceeding by the vacancy mechanism are considered. To ensure the neutrality of the total electric current arising during the movement of ions, a certain ratio of vacancies in cation and oxygen is required. Since oxides usually have an excess of oxygen vacancies at high temperatures, a further increase in their concentration due to the introduction of appropriate additives slows down diffusion, prevents the polymorphic transition, and stabilizes the phase. The introduction of additives leading to an increase in the concentration of vacancies in the cation, on the contrary, accelerates diffusion and promotes the polymorphic transition. Bibliography: 10 titles.