Abstract: The roles and effects of Mg addition in perovskite oxygen sensing ceramic are studied. The Mg contents in SrTiO₃ are taken as different. It was measured that the dependence of resistance on temperature and oxygen sensing behavior at different temperatures and oxygen partial pressures. The characteristic of adsorbed oxygen on the specimens is investigated by means of TPD. Where there is substitution of Mg²⁺ at the Ti⁴⁺ site, the p-type region of SrTiO₃ ceramic can be expanded, extrinsic oxygen vacancy can be produced and solid solubility limit of acceptor can be raised simultaneously. The exchange quantity of oxygen is increased between specimen and ambient, so it is possible to obtain SrTiO₃ exhibiting high oxygen sensitivity. However, a part of addition of Mg above 20mol% increases resistivity because of Sr₂TiO₄ segregation.

Key words: perovskite, oxygen-sensing materials, magnesium, functional ceramics