Effect of annealing on structural and optical properties of Ni(1−x)MnxO nanostructures thin films

Nanostructured Nickel−Manganese oxide (Ni(1−x)MnxO) thin films, where (x=0%, 2%, 4%, 6% and 8%) have been prepared by a simple and inexpensive chemical spray pyrolysis technique (CSP) on glass substrates at a temperature of (400 °C) and thickness of about (300 nm). The effect of annealing on structural properties has been investigated. The structural properties of these films have been studied using X-ray diffraction. The X-ray results showed that all films before and after annealing are polycrystalline in nature with cubic structure and preferred orientation along (111) plane. The average crystallite size (Dav) was calculated using Scherrer formula for Nickel−Manganese oxide (Ni(1−x)MnxO) thin films before and after annealing and it is found that the (Dav) increases as the Mn-concentration increases and increases after annealing too, and the (Dav) values after annealing were in the range of (11.260−19.943) nm. The Structural parameters including (Lattice Constant (a○), Dislocation Density (δ), Number of Crystal Per Unite area (No) and Texture coeffecient (Tc) were also calculated. AFM results showed the average grain size estimated from the AFM granularity report confirms the XRD results. The optical properties of the films prepared before and after annealing were studied by recording the transmittance and absorbance spectrum in the range of (300−900) nm, the results showed that the absorbance increases with increasing the percentage of doping and it is also found that the energy band gap for the allowed direct transition decreass with increasing the percentage of doping for all films prepared before and after annealing and the values were in the range of (3.59-3.53 eV) before annealing and increased to the range of (3.64-3.57 eV) after annealing.