Electrical and gas sensing properties of Li and Ti codoped NiO/PVDF thin film

In this study the electrical and gas sensing properties of Li and Ti codoped NiO (LTNO)/polyvinylidenefluoride (PVDF) nanocomposites were investigated. LTNO with a composition of Li_0.1Ti_0.018Ni_0.882O was prepared using citrate-gel technique. Phase evolution of as-prepared and calcined powders were examined by XRD technique and single phase NiO was obtained at 500 °C. TEM investigation revealed that the size of particles ranged from 5 to 40 nm. Thin films of LTNO/PVDF nanocomposite were synthesized using spin coating method. The electrical properties of film were investigated as a function of temperature. It was observed that the ln σ_dc-1/T graph consists of two different linear regions. While room temperature impedance spectra of film consist of a curved line, a transformation into a full semicircle with increasing temperature was observed from the complex plane plots of impedance. From the analysis of frequency, f, dependence of electrical conductivity, σ_ac, it was found that the σ_ac obeys the power law given by σ_ac = σ₀ω^s, in which the frequency exponent s decreases with temperature. The sensing properties of the film for NH₃ were also investigated. It was observed that the conductivity (dc and ac) strongly dependent on the presence of the NH₃ gas.