Cr2−xTixO3 (x ≤ 0.5) as CH3COCH3 sensitive resistors

Fine powders of Cr2−xTixO3 (x = 0–0.5, CTO) were prepared by combustion technique, followed by heat treatment at 1000 °C in ambient air. The XRD results showed the presence of a solid solution of TiO2 in Cr2O3 as the major phase along with CrTiO3 as the minor phase for x ≥ 0.4. EDAX studies on Cr2−xTixO3 (x = 0.1 and 0.3) suggested the composition of the oxides close to the theoretical values. The XPS studies showed the presence of Cr3+ and Ti4+species on the surface. Ti4+ inclusion in the eskolait Cr2O3 had significant influence on the activation energy for conduction (Ea) at 100–700 °C in air. The commercial Taguchi sensors coated with CTO, when subjected to acetone in ambient air, showed an abrupt change in resistance within 10 s and took the same time for recovery at 400 °C. Different humidity levels were achieved by various water vapor buffers thermostated at room temperature where sensor response decreased nearly by 40% at 80% RH. The stability test indicated the first order exponential decay to a constant sensor potential value of 4.7. The origin of the gas response was attributed to the surface reaction of (CH3)2CO to form an intermediate geminal diol, followed by formation of an unstable ethanoyl radical and then final product CH3COOH, which was desorbed as a gas at 400 °C.