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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 (Co 3 O 4) 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 Co 3 O 4 and ~ 60-75% for all doped samples). The optical band gaps were found to be (E g1 = 1.50 eV, E g2 = 2.20 eV) and (E g1 = 1.42 eV, E g2 = 2.07 eV) for the case of (pure Co 3 O 4 and 9% Ni-doped Co 3 O 4) respectively. The complementary phase information is provided by FT-IR spectroscopy. FT-IR spectra confirms the presence of Co 2+-O and Co 3+-O vibrations in the spinel lattice. The Nyquist plots suggests that the equivalent circuit of our films is an parallel circuit R p C p. It was found that the resistance Rp decreases whereas the capacity Cp increases with increasing doping levels.

Cu-doped Cr2O3 thin films were deposited onto glass substrate by the sol–gel dip-coating (SGDC) process using dopant values of 0, 3, 6, 9 and 12%. The Chromium (III) Nitrate Nonahydrate [Cr(NO3)3·9H2O] was used as a Cr source, whilst for the dopant, the corresponding nitrate (Cu(NO3)2) was used. The crystal structure, as well as the optical and electrical properties were examined. XRD data showed that the films with a high degree of crystallinity were rhombohedral Cr2O3 phase. The crystallite size reduces with increase in Cu doping proportion. The AFM results indicate a decrease in the surface roughness of the doped Cr2O3: Cu thin films. The UV-Vis spectra of the Cu doped-Cr2O3 films showed high transparency in the visible region. The optical band gap of Cr2O3 thin films decreases with increasing in Cu doping rate. The Nyquist plot shows that the equivalent circuit of Cu doped-Cr2O3 films is a parallel circuit RpCp. As the concentration of Cu increases, Resistance RP regresses while capacitance Cp increases.

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In this article, manganese-doped cobalt oxide (Mn-doped Co3O4) thin films have been prepared on glass substrates using sol gel-based dip-coating technique in order to investigate their optical, structural and electrical properties. The Mn concentration was changed from 0 % to 9 %. The synthesized samples were characterized by ultraviolet-visible spectroscopy (UV-visible), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and complex impedance spectroscopy to elucidate the optical, structural, vibrational and electrical properties. Our optical results show that the transmittance of Mn-doped Co3O4 films decreases with increasing doping levels. The optical band gaps were found to be ({E_{g1}} = 1.51{\ }eV, {E_{g2}} = 2.12{\rm{ eV}}) and ({E_{g1}} = 1.23{\ }eV, {E_{g2}} = 1.72{\rm{ eV}}){\ }for the case of undoped Co3O4 and 9 % Mn-doped Co3O4, respectively. This shift means that the impurities would create energy levels. The structural analysis provides evidence that obtained powders were crystallized in cubic spinel structure. The complementary phase information is provided by FTIR spectroscopy. The FTIR study depicted the presence of four distinct bands characterizing Mn-doped Co3O4 cubic spinel-type structure. The Nyquist plots suggest that the equivalent circuit of Mn-doped Co3O4 films is an RpCp parallel circuit. It was found that the effective resistance Rp decreases, whereas the effective capacitance Cp increases with doping.