Synthesis, characterization and low concentration ethanol sensing performance of sol–gel derived La(III) doped tin oxide

Abstract

Nanocrystalline undoped and lanthanum(III) doped (2, 4 and 6 at%) tin oxide powders were synthesized using sol-gel processing from their water based precursor sols. Microstructures and surface morphologies of all powders were characterized using X-ray diffractometer, BET surface area, UV-Visible spectrophotometer, scanning and transmission electron microscope along with energy dispersive X-ray diffractometer. XRD and UV-Vis spectral analyses revealed decrease of tin oxide crystallite size on La(III) doping. 4 at% La(III) doped powder showed *5 nm average particle size and *42 m 2 /g surface area respectively. A systematic comparison study revealed that sensors made from 4 at% La(III) doped SnO 2 powder exhibited optimum ethanol vapor sensing performance at operating temperature, 350°C (response *70 % for 10 ppm ethanol) with excellent response and recovery times. Even for very low concentration ethanol vapour (1 ppm) response observed was *53 %. A possible mechanism for enhancing sensitivity on La(III) doping has been discussed.