Studies on Gas Sensing Performance of Pure and Surface Modified SrTiO sub( 3) Thick Film Resistors

Strontium Titanate (SrTiO sub( 3) (ST)) was prepared mechanochemically from Sr(OH) sub( 2) and TiO sub( 2). XRD confirms the Perovskite phase of material. Thick films of ST were prepared by screenprinting technique. The gas sensing performances of thick films were tested for various gases. It showed maximum sensitivity to CO gas at 350 degree C 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 H sub( 2)S gas (100 ppm) at 300 degree C 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.