Bead structured nanocrystalline ZnO thin films: Synthesis and LPG sensing properties

ZnO beads are prepared by spray pyrolysis method on glass substrates and their liquefied petroleum gas (LPG) sensing properties are studied. XRD patterns show that the films are polycrystalline having hexagonal wurtzite crystal structure with strong c-axis orientation. The grain size is estimated to be nearly 13 nm. SEM shows bead like structures scattered throughout the surface having a circular pore in the centre serving as gas adsorption sites. The LPG sensing properties of the ZnO films are investigated at different operation temperatures, for different concentration of LPG. A maximum sensitivity of 82% is obtained at 350 °C for 0.8 vol.% with rapid response and recovery characteristics. These experimental results show that ZnO beads of nanocrystallites are promising LPG sensor.