INFLUENCE OF THE OXYGEN PARTIAL-PRESSURE IN THE REDUCING GAS ON SRTIO3 SEMICONDUCTOR CERAMICS

SrTiO3 ceramics were sintered under various oxygen partial pressures. The relationship between the oxygen partial pressure and properties of sintered samples was investigated by TEM, EDX and XRD measurements. A t lower oxygen partial pressure, the Ti8O15 phase about 5 mum in diame ter existed at triple points. On the contrary, at higher oxygen partia l pressure the Ti3O5 phase about 0.5 mum in diameter existed at triple points. The stability of Magneli phases was discussed on the basis of thermodynamic data. Lowering of oxygen partial pressure resulted in a n increase in oxygen vacancies and lattice parameters and further in a decrease in electric resistivity.