General model for the functional dependence of defect concentration on oxygen potential in mixed conducting oxides

To understand and engineer applications for mixed conducting oxides, it is desirable to have explicit, analytical expressions for the functional dependence of defect concentration and transport properties on the partial pressure of the external gas phase. To fulfill this need, general expressions are derived for the functional dependence of defect concentration on the oxygen partial pressure (P-O2) for the mixed ionic electronic conductors. The model presented in this paper differs from expressions obtained using the popular Brouwer approach because they are continuous across multiple Brouwer regions.