Sensing behaviour of tin doped chromium oxide gas sensor toward ethanol

In this paper, the enhancement of gas sensing response due to addition of tin into Cr2O3 has been reported. Sn-doped Cr2O3 nanoparticles have been prepared by a co-precipitation method and characterised by X-ray diffraction, field emission scanning electron microscopy and energy dispersive X-ray analysis. X-ray diffraction studies revealed the substitution of Cr3+ ions by Sn4+ ions. Field emission scanning electron microscopy images exhibited presence of clusters and agglomerates on the surface. The concentration of tin, used as dopant, was varied from 1 to 5 wt.% and its effect on gas sensing response has been studied. Synthesised powders were applied as thick film onto alumina substrate and tested for ethanol sensing at different operating temperatures and all the sensors gave an optimum response at 250 ∘C. The activation energy of conduction for all the samples was estimated using Arrhenius plots and it was observed that the sample doped with 4 wt.% Sn possesses minimum activation energy, and interestingly this sample gave the best sensing response in the lot.