An approach to the defect chemistry of barium titanate

Abstract

In ternary oxides, the concentrations of point defects that are responsible for departures from stoichiometry depend upon three thermodynamic variables under a constant total pressure. These are the temperature and two activities that may be chosen as the oxygen partial pressure and the activity of one oxide component. A new representation of majority defects pairs is developed in a two-dimensional space, the coordinates of which are related to these activities. The effect of a constant cationic composition is analysed with the help of such diagrams, which appear complementary to those used in the case of simpler binary metal oxides. Barium titanate has been chosen for a specific application of these ideas.