Electrical properties and acetone-sensing characteristics of LaNi1-xTixO3 perovskite system prepared by amorphous citrate decomposition

Perovskite type oxides LaNi1-xTixO3 (X =0.0-1.0) were prepared by thermal decomposition of amorphous citrate precursors followed by annealing at 700-1000 degrees C in ambient air. These products were characterized by various analytical methods such as XRD, FT-IR, EDAX, SEM and XPS. Ti in the LaNi1-xTixO3 had significant influence on the crystal size of the nanocrystals and the activation energy (E,)which was measured at 50-800 degrees C in air atmosphere. The LaNi1-xTixO3 system showed an interesting metal-insulator transition with increasing Ti concentration, which can be adjusted to enhance the response and selectivity of the materials to acetone. The LaNi0.5Ti0.5O3-based sensor exhibited a quick change in the resistance to 1-5 ppm acetone within 40 s and took less than 70 s for recovery at 350 degrees C, which could hardly be influenced by the environmental humidity. The XPS analysis results showed that the adsorbed oxygen on the Surface of sensing material and its concentration are the important factors for the acetone detection. The origin of the gas response is attributed to the thermal reaction, which occurs between acetone and adsorbed oxygen species, forming an acetone-oxygen complex, and then the final product CH3COOH is desorbed as a gas at 350 degrees C. (C) 2009 Elsevier B.V. All rights reserved.