Thick film of LaCr1−xTixO3 (x ≤ 0.4) perovskites prepared by combustion technique for alcohol sensing application

Fine perovskite powders of LaCr1−xTixO3 (LCTO) (x ≤ 0.4) were obtained by citrate combustion technique and characterized. Powder XRD patterns showed an orthorhombic structure for all the products. SEM images of the sensors treated at 850 °C had the grain size in the range of 200–340 nm for isolated grains on the surface, which was further evidenced by the range of 210–333 nm obtained from Scherrer equation. The ac impedance measurement was used to identify the conduction process in the temperature range of 400–600 °C, followed by activation energy (Ea) determination, which was found to be in the range of 0.05–0.32 eV. LaCr1.8Ti0.2O3 exhibited the maximum sensor relative responses of 525, 476 and 438% in the presence of 30 ppm of i-C3H7OH, C2H5OH and CH3OH, respectively. The sensors responded within 19–45 s, whereas the recovery time was in the range of 60–200 s. The gas response is believed to be due to the surface catalytic reaction of alcohol vapors with O(ads)− at the working temperature of 400 °C.