Electrical conduction and oxygen sensing mechanism of Mg-doped SrTiO3 thick film sensors

The dependencies of the electrical conduction of Mg-doped SrTiO3 thick film samples on temperature and oxygen partial pressure have been studied. The Mg contents in SrTiO3 were 10 mol%, 20 mol%, 30 mol%, 40 mol% and 50 mol%, respectively. The experimental results show that all samples exhibit p-type semiconduction in the pO2 region 3.8×10−4–2.6×10−1 atm and temperature range 500–900°C. The temperature at which a maximal resistance is observed decreases from 300°C to 100°C in Mg-doped SrTiO3 samples. The 40 mol% Mg-doped SrTiO3 sample reveals the best oxygen sensing properties. Results are discussed based on the X-ray diffraction and the analysis of defect chemistry.