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Description
Nickel-doped calcium copper titanate (CaCu3Ti4O12: CCTO) thin films were synthesized by a sol-gel method. All films were spin-coated with four layers on silicon and alumina substrates, and each film layer was annealed at a fixed annealing temperature of 800 °C. The obtained samples with different doping concentrations (0-7.27 wt%) were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoe-lectron spectroscopy (XPS). From XRD patterns, CCTO and Ni-doped CCTO films were cubic perovskite phase with small amount of impurity phases of TiO2. The film thickness of approximately 320-600 nm were obtained using FE-SEM. In addition, 7.27 wt% Ni-doped CCTO film showed more porosity than other films. The film gas sensors were probed to measure gas sensing responses towards different types of gases such as NO2, H2, NH3, H2S and ethanol gas. All samples performed the best selectivity towards H2S. Compared with other films, the 7.27 wt% Ni-doped CCTO film sensors exhibited the highest response of 112 for 10 ppm of H2S with the optimum temperature of 250 °C.
