Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Abstract

The diagrams of the concentrations of point defects, determined for a series of temperatures, for the oxides: Mn 1-δ O, (1173-1830 K), Co 1-δ O (1223-1673 K) and Ni 1-δ O (1273-1673 K), whilst taking into consideration simple defects and defect clusters of type (2:1), (4:1), (6:2), are presented in this work. A new method was used for the calculations of the diagrams and the results of the studies of the deviation from the stoichiometry obtained by many authors were used in the calculations. The values of Go of the formation of the individual defects and clusters were determined; their temperature dependencies were also determined. The calculations show that in the studied oxides the maximal concentration of defect clusters is lower than the concentration of single-ionized cation vacancies. At the lowest temperatures studied, the concentration of clusters is comparable to the concentration of electroneutral vacancies. The ratio of these concentration decreases with the temperature increase. The presence of defect clusters only slightly decreases the concentration of cation vacancies. The ratio of the concentrations of defect clusters varies with the temperature. This ratio is different for the individual oxides.