DEFECT STRUCTURE OF Co3O4 COBALT OXIDE

The deviation from stoichiometry, y, in the Co3O4 oxide has been studied as a function of temperature (973-1173 K) and oxygen pressure (30-10(5) Pa) using microthermogravimetric technique. It has been found that at low oxygen pressures, the deviation from stoichiometry decreases with increasing oxygen pressure, reaching zero value in intermediate oxygen pressure range and for higher pressures it starts to increase. This behaviour strongly suggests the presence of complex defect structure in the studied oxide. At very low oxygen pressures, close to the dissociation pressure of the oxide, interstitial cations are the predominant ionic defects, while at high pressures cation vacancies predominate. Using the obtained results of nonstoichiometry, the concentrations of predominant point defects in the studied oxide have been calculated as a function of temperature and oxygen pressure.