Electrical conductivity and defect structure of pure and Li-doped CoO at high temperatures

A statistical analysis of recent data on the electrical conductivity of CoO at 1000-1400° C is developed using a defect model involving the presence of aggregates of the 4 1 type between vacancies and metal interstitials in addition to the isolated vacancies but disregarding the defect-defect interactions. The results indicate the presence of significant concentrations of these defects in pure CoO at high oxygen pressures, in agreement with the theoretical predictions. A similar analysis of the data for Li-doped CoO indicates that in the doped samples these defects may also contain impurities in the interstitial site. Equilibrium constants for the formation of the various defects are obtained as functions of temperature.