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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 R p C p . As the concentration of Cu increases, Resistance R P regresses while capacitance C p increases.

Thin films of Co-doped [Formula: see text]-MnO2 have been deposited on Pyrex glass substrates by the sol–gel dip-coating method with Co concentrations of 1, 3, 5 and 7 at.%. The deposited thin films were characterized for their structural, morphological, optical and electrical properties. The XRD spectra confirm that all the samples have tetragonal phase of [Formula: see text]-MnO2. FTIR spectra reveal the presence of Mn–O in all of the samples. AFM measurements indicate that the surfaces of films have been affected with cobalt content incorporation. Transmittance spectra of the undoped and Co-doped MnO2 thin films were recorded by a UV–vis spectrometer. Optical gap was found to be in the 2.60–2.51-eV scale. This decrease is due to the presence of manganese vacancies and/or oxygen defects. From the complex impedance measurements that show semicircular arcs at different cobalt contents, an equivalent parallel [Formula: see text] electrical circuit has been proposed.

This paper presents the results of an experimental work devoted to the synthesis and the characterization of cobalt oxide (Co3O4) thin layers doped with transition metal (TM = Ni, Mn, Cu) in order to investigate their structural, optical and electrical properties. The materials were synthesized by the sol–gel method and deposited by dip-coating process. The synthesized samples were characterised by Ultraviolet-visible spectroscopy (UV–visible), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Complex impedance spectroscopy to elucidate the optical, structural, vibrational and electrical properties. Our structural results show that the materials kept their cubic spinelle structure with preferred orientation of (311), Our optical results show that the transmittance of all doped samples decreases compared to undoped Co3O4 and the doping leads to a reduction of their band gap energies. The complementary phase information is provided by FT-IR spectroscopy. FT-IR spectra of TM-doped Co3O4 confirms the presence of Co2+ − O and Co3+ − O vibrations in the spinel lattice. The Nyquist plots suggest that the equivalent circuits (parallel circuit of Rp and Cp) of our films are not qualitatively affected by the doping, but it was found that the effective resistance Rp decreases whereas the effective capacitance Cp increases with doping.

This work shows an investigation of tin-doped Mn2O3 thin layers synthesized via sol–gel process and deposited on glass substrates using dip-coating technique. The Sn concentration was changed from 0% to 9%. The obtained samples were characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR), Ultraviolet–Visible spectroscopy (UV–Vis) and impedance spectroscopy (IS). XRD showed that Mn2O3 was crystallized in the cubic form with directionally preferential orientation structure (222). The formation of Mn2O3 was also confirmed by FTIR spectroscopy. The optical transmittance of the samples is greater than 70% and increases following doping, while the band gap energy decreases with an increase in Sn doping concentration. Complex IS indicates that the resulting circuit is a parallel RpCp where Cp is the capacitance of the layer and Rp its resistance.

Undoped and Mn-doped TiO2 thin films have been prepared by sol–gel dip-coating technique on glass and silicon substrates. X-ray diffraction studies showed that both TiO2 and Mn-doped TiO2 thin films are of anatase phase with (101) as preferential orientation. All films exhibit high transparency ([Formula: see text]80%) over the visible range. The optical bandgap decreases from 3.66[Formula: see text]eV to 3.52[Formula: see text]eV due to the extent of electronic states introduced by doping. Infrared transmission spectra showed Ti–O (625[Formula: see text]cm[Formula: see text]) and Ti–O–Ti (495–436[Formula: see text]cm[Formula: see text]) bands. Thermal analysis revealed endothermic reactions between 94∘C and 110∘C and exothermic reactions between 406∘C and 443∘C. The Nyquist plots depicted that equivalent circuit of the films is an [Formula: see text] parallel. The resistance [Formula: see text] decreases while the capacitance [Formula: see text] increases with Mn-doping.

This paper contains the results of the structural and spectroscopic characterizations of undoped and Cadmium-doped cobalt oxide thin films with different Co/Cd molar ratios (3%, 5%, 7% and 9%). The nanosized undoped and cadmium-doped Co3O4 thin layers were prepared using sol–gel process and deposited on glass substrates by dip coating. The changes caused by the incorporation of cadmium at different levels of doping have been highlighted by the techniques UV–Visible (UV–Vis) spectroscopy, Infrared (IR) spectroscopy, X-ray diffraction (XRD) measurements, SEM coupled EDX and impedance spectroscopy. From the UV–Vis spectroscopy analysis, it was found that all the films are two direct bandgap energies. The optical transmittance and the bandgap energy decrease with increase in Cd concentration. The XRD spectra confirm the films were polycrystalline with a cubic spinel structure. The results of the impedance spectroscopy show that the equivalent circuit of the synthesized samples is an RC parallel circuit.

Antimony-doped tin oxide thin films have a range of technological applications as conductive coatings, and sol–gel processing seems to offer some advantages over other coating techniques. In this study antimony-doped tin oxide (ATO) thin films have been prepared by the sol–gel dip-coating (SGDC) process, using tin (II) chloride dehydrate (SnCl 2 , 2H 2 O) and antimony (III) chloride (SbCl 3 ) as host and dopant precursors respectively. The structure of the (ATO) powders was analysed by X-ray diffraction (XRD) and the microstructure of the thin films by atomic force microscopy (AFM). These investigations show that the structure is tetragonal rutile type and that an increase in Sb-doping decreases the crystallite size of the (ATO) particles. To analyze the impedance spectroscopy data, the Nyquist ( Z ″ vs . Z ′) plots as well as the representation of imaginary ( Z″ ) and real ( Z ′) parts of impedance vs. frequency were used. The Nyquist plots suggest that only the grain boundaries are responsible in the conduction mechanism of the material. From the variation of lnσ vs. inverse of absolute T we have deduced the activation energy found to be 0.87 eV.

This work presents an experimental study dedicated to the synthesis and characterization of pure and Ni-doped chromium (III) oxide thin films. Sol–gel thin films with doping rates of 3%, 6%, 9%, and 12% were deposited onto glass substrates by the dip-coating method at room temperature using Cr(NO3)3: 9H2O as precursor. Using X-ray diffraction (XRD), infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Vis), and impedance spectroscopy on solids, we noted that the films are polycrystalline with a grain size ranging from 11.2[Formula: see text]nm to 24.4[Formula: see text]nm, the synthesized materials are highly transparent in the visible light with more than 90% of transmittance and have an optical bandgap less than 3.0[Formula: see text]eV overall, and the equivalent circuit of the deposited films is a resistors and capacitors (RC) parallel circuit.

This paper presents the results of an experimental work devoted to the synthesis and the characterization of tin dioxide (SnO[Formula: see text] thin layers doped with group-IA elements (Li, Na and K). The materials were synthesized by the sol–gel method and deposited by dip-coating, using tin (II) chloride dihydrate as a source of tin and absolute ethyl alcohol as solvent. Thin films prepared were characterized by several techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (IR), visible and ultraviolet spectroscopy and complex impedance method. The results obtained show that the materials kept their tetragonal rutile structure with preferred orientation of (101), whereas doping leads to a reduction of their energy band gap. The complex impedance analysis suggests that the different processes occurring at the electrode interface are modeled by an electrical circuit not affected by the doping.

Undoped and Ni-doped TiO 2 thin films have been prepared by sol-gel dip-coating method on glass and silicon substrates. X-ray diffraction studies show that both TiO 2 and Ni-doped TiO 2 thin films are of anatase phase with (1 0 1) as preferential orientation. From the UV-visible spectroscopy analysis, all films exhibits a high transparency ~ 80% and shows that the optical band gap decreases from 3.66 to 3.59 eV, which may be related with the phase composition and impurities. Fourier transformed infrared spectroscopy (FTIR) study confirms the presence of Ti-O, Ti=O and O-H bands. Thermal analysis by differential scanning calorimetriy (DSC) shows endothermic reactions between 30 °C and 280 °C and exothermic reactions between 370 °C and 540 °C corresponding to the crystallization of TiO 2 in the anatase phase. The Nyquist plots suggests that the equivalent circuit of the films is an R p C p parallel circuit and shows an increase in resistance R p with increasing the Ni concentration and a decrease in capacity C p .

Thin films of antimony-doped tin oxide (ATO) have been prepared by the sol-gel dip-coating (SGDC) process, using tin(II) chloride dehydrate (SnCl2, 2H2O) and antimony (III) chloride (SbCl3) as host and dopant precursors respectively. The effect of antimony doping on the structural, thermal, electrical and optical properties of the samples were investigated. The structure of the (ATO) powders was analysed by X-ray diffraction (XRD) and the microstructure of the thin films by scanning electron microscopy (SEM). It was clear from these investigations that its structure is tetragonal rutile type and that an increase in Sb-doping decreases the crystallite size of the (ATO) particles. Thermal analysis by differential scanning calorimetry (DSC) showed that the crystallization temperature is about 370 °C whatever the Sb-doping amount. The lowest resistivity (2.6 × 10−3 cm) was obtained for the 5% Sb-doped film and the value of the band gap (3.69 eV) for the undoped film, increases slightly with Sb-doping increasing for the doped films.