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Effect of Aqueous Solution Molarity on Structural and Optical Properties of Ni0.92Co0.08O Thin Films Prepared by Chemical Spray Pyrolysis Method |
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PP: 111-119 |
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Author(s) |
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Nabeel A. Bakr,
Ziad T. Khodair,
Ahmed M. Shano,
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Abstract |
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| In this study, Ni0.92Co0.08O thin films with different molarities (0.05M, 0.1 M, 0.15M and 0.2 M) have been successfully deposited on glass substrates by chemical spray pyrolysis (CSP) technique at substrate temperature of (400 oC) and thickness of about 300 nm. The structural and optical properties of these films have been studied using XRD, AFM, and UV-Visible spectroscopy. The XRD results showed that all films are polycrystalline in nature with cubic structure and preferred orientation along (111) plane. The crystallite size was calculated using Scherrer formula and it is found that the 0.2M has maximum crystallite size (49.51nm). AFM results showed homogenous and smooth thin films. The absorbance and transmittance spectra have been recorded in the wavelength range of (300-900) nm in order to study the optical properties. The optical energy gap for allowed direct electronic transition was calculated using Tauc equation and First derivative of absorbance with respect to energy of photon. It is found that the band gap decreases when the molarity increases and the band gap values ranges between 3.60 eV and 3.54 eV for the prepared thin films. The Urbach energy increases as the molarity increases and the Urbach energy values range between 439 meV and 680 meV. The optical constants including (absorption coefficient, real and imaginary parts of dielectric constant) were also calculated as a function of photon energy. Refractive index and extinction coefficient for the prepared thin films were estimated as a function of wavelength. |
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