The effects of annealing temperature on the sensing properties of low temperature nano-sized SrTiO3 oxygen gas sensor

A low temperature SrTiO3 oxygen gas sensor was fabricated by high-energy ball milling and conventional screen-printing techniques. The thermal stability, grain size and lattice constant of the material and the sensing properties of sensor device at different annealing temperatures were studied using DTA/TGA, XRD, TEM and the gas sensor characterization system, respectively. The results show that the annealing temperature affects only the grain size of the synthesized nano-sized SrTiO3 material but does not change its perovskite structure, confirming the thermal stability of the synthesized material. The sensing properties of sensor device are affected by the annealing temperature due to the change of the grain size of the material. The optimal relative resistance (Rnitrogen/R20% oxygen) value of 6.35 is obtained for the synthesized SrTiO3 sample annealed at 400 °C and operating at 40 °C. The 40 °C optimum operating temperature is much lower than that for the conventional metal oxide semiconducting oxygen gas sensors (300-500 °C).