Sol–gel processed (Mg–Zn–Ti) oxide nanocomposite film deposited on prism base as an opto-electronic humidity sensor

Nanocrystalline (Mg–Zn–Ti) oxide films were deposited on an equilateral prism using sol–gel spin process and then annealed at 450 °C for 4 h. The humidity sensing properties of the films were investigated at different angles of incidence. It was observed that the intensity of reflected light increased with an increase in relative humidity (%RH) in the range 10–95% at a particular angle of incidence, which is quite significant for sensor fabrication purposes. The X-ray diffraction reveals the formation of TiO2, ZnTiO3 and MgTiO3 nanocomposites having minimum crystallite size 14 nm. UV–vis absorption spectroscopy was used for optical characterization of the film. It was found that the optical band gap of the composite material was 3.925 eV. Surface morphological study of the film and compositional analysis of elements were carried out using scanning electron microscopy and energy dispersive X-ray spectroscopy. The average sensitivity and reproducibility of the sensor for θi = 60° were found 2 and ∼88%, respectively. Response and recovery time of the sensor were 18 and 30 s respectively. These experimental results have well matches with the theory.