Structural, morphological and gas sensing properties of undoped and Lanthanum doped nanocrystalline SnO2

Undoped and Lanthanum doped tin dioxide nanopowders were successfully synthesized by a chemical co-precipitation method. The TGA–DTA, XRD, TEM, SEM, EDAX, FTIR, Raman and UV–vis techniques were used to characterize various physico-chemical properties of samples. Thick films of functional material were prepared by using a screen printing technique and then sintered at 650 °C for 2 h. XRD analysis of all the samples revealed formation of single phase rutile type tetragonal structures which was further supported by Raman studies and FTIR measurements. The particle size of sintered SnO2 was decreased with La doping, confirming the role of La as a grain growth inhibitor. Morphological studies revealed formation of porous structure useful for gas sensing application. Gas sensing characteristics were investigated towards various reducing gases such as liquefied petroleum gas (LPG), acetone (CH3COCH3), ethanol (C2H5OH) and ammonia (NH3). The maximum response was exhibited by 3 mol% La doped SnO2 thick film towards acetone vapor at an operating temperature of 300 °C. The sensor exhibited quick response and recovery times which were 20 s and 48 s, respectively.