Sprayed CdO thin films for liquefied petroleum gas (LPG) detection

Nanocrystalline cadmium oxide (CdO) thin films were deposited onto glass substrates by a chemical spray pyrolysis method using an aqueous solution of cadmium acetate. These films were characterized for their structural and morphological properties by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The CdO films are oriented along (1 1 1) plane with the cubic crystal structure. These films were utilized in liquefied petroleum gas (LPG) sensors. The dependence of the LPG response on the operating temperature, LPG concentration and CdO film thickness was investigated. The CdO film showed selectivity for LPG over N2 compared to CO2 ( S LPG / S N 2 = 11.3     and     S LPG / S C O 2 = 1.88 ) . The maximum LPG response of 34.11% for the film of thickness 0.97 μm at gas concentration of 0.16 vol.% at 698 K was achieved. Additionally, the stability of films has been studied.