Structural, optical and electrical properties of Ni-doped Co3O4 prepared via Sol-Gel technique

<div><p>In this article, Nickel doped Cobalt oxide thin films and powders have been prepared on glass substrates using sol gel based dip coating process in order to investigate their optical, structural and electrical properties. The Ni concentration was changed from 0 to 9 wt(%).The synthesized samples were characterised by Ultraviolete visible analysis, X-ray diffraction, Fourier transform infrared spectroscopy and Complex impedance spectroscopy to depict the optical, structural, vibrational and electrical properties. Our structural results show that the obtained samples were composed of (Co3O4) polycrystalline with spinel-type preferentially oriented in the (311) plane. Our optical results show that the films have high transparency over the visible region (85% for Co3O4 and ∼ 60-75% for all doped samples). The optical band gaps were found to be (Eg1 = 1.50 eV, Eg2 = 2.20 eV) and (Eg1 = 1.42 eV, Eg2 = 2.07 eV) for the case of (pure Co3O4 and 9% Ni-doped Co3O4) respectively. The complementary phase information is provided by FT-IR spectroscopy. FT-IR spectra confirms the presence of Co2+-O and Co3+-O vibrations in the spinel lattice. The Nyquist plots suggests that the equivalent circuit of our films is an parallel circuit RpCp. It was found that the resistance Rp decreases whereas the capacity Cp increases with increasing doping levels.</p>