Mixed conductivity evaluation and sensing characteristics of limiting current oxygen sensors

Strontium titanate based materials are promising candidates for fabrication of oxygen sensors. As a dense diffusion barrier layer of limiting current oxygen sensor, strontium titanate based materials should be able to control the diffusion rate of oxygen ions or accelerate the formation of limiting current. Based on this key question, indium oxide was introduced to strontium titanate based materials and then Y_0.08Sr_0.92Ti_0.6Fe_0.4-xO_3-δ/x/2 In₂O₃ (x = 0.04, 0.06, 0.08) composites were prepared. To understand the efficacy of doping indium oxide on the physical and sensing properties of the strontium titanate, the ionic and electronic conductivity were intently investigated. The obtained results demonstrated that the ionic and total conductivity simultaneously increased upon increasing the concentration of indium oxide dopant. Increasing the content of In₂O₃ accelerates the occurrence of limiting current of the sensor at lower voltages and then elevate the working life of the sensor.