Gas sensing performance of pure and modified SrTiO3 thick film resistors

Strontium titanate (SrTiO3 (ST)) was prepared mechanochemically from Sr(OH)2 and TiO2. XRD confirms the pervoskite phase of material. Thick films of ST were prepared by screen-printing technique. The gas sensing performance of thick films were tested for various gases. It showed maximum sensitivity to CO gas at 350degC for 100 ppm gas concentration. To improve the sensitivity and selectivity of the film towards a particular gas, ST thick films were surface modified by dipping them in a solution of nano copper for different intervals of time. These surface modified ST films showed larger sensitivity to H2S gas (100 ppm) than pure ST film. A systematic study, of sensing performance of the sensor, indicates the key role-played by the nano copper species on the surface .The sensitivity, selectivity, response and recovery time of the sensor were measured and presented.