Structural and gas sensing behavior of (Sn0.3Ti0.7)O2 based gas sensor

In this work we report the synthesis, microstructure, electric properties and sensing performance of (Sn 0.3 Ti 0.7 )O 2 powder, were chemically prepared by solid solution route. Thick films were prepared by screen-printing technology. The surfaces of the films were modified by dipping them into an aqueous solution of copper chloride for different intervals of time, followed by firing at 550°C for 30 min. Pure film showed response to CO 2 at 300°C and CuO-modified films have been found to be highly selective towards H 2 S at 200°C. The surface modification, using dipping process, altered the adsorbate-adsorbent interactions, which gave the unusual sensitivity and selectivity effect. The characterization of the films was done by Scanning Electron microscopy, X-ray diffraction and Thermal gravimetric analysis. Single peaks of the X-ray diffraction pattern reveals that the formation of compound of (Sn 0.3 Ti 0.7 )O 2 . Average crystallite size was found to be 40.7 nm of pure film and of CuO-modified film was 31.2 nm. The role played by surface copper species in the gas sensing performance is discussed. Grain size, electric properties and gas sensitivity of the films were measured and presented.