Impact of gamma radiation on the linear and nonlinear optical properties of PVA/CMC/ZnS-NiO nanocomposite films

Abstract

In the present study, we used the sol-gel and ex-situ casting techniques to prepare a nanocomposite (NC) of polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), Zinc sulfide (ZnS) and nickel oxide (NiO) nanoparticles (NP). The Rietveld modification of XRD records indicated that the prepared ZnS and NiO had a nanonature of average particle size 4 and 18 nm, respectively. Samples from the prepared PVA/CMC/ZnS-NiO NC were irradiated with γ doses ranging from 15 to 90 kGy. The resulting impact of γ radiation on the optical properties of the NC films was studied using ultraviolet spectroscopy and the International Commission on Illumination (CIE) color difference technique. When the γ dose increased up to 90 kGy, both the direct and indirect bandgaps decreased. The Urbach energy exhibited a reverse trend. This could be attributable to the dominance of chain crosslinks. In addition, we used the optical dielectric loss (ε″ ) to identify the type of microelectronic transition for the NC samples, which was found to be a direct allowed transition. Also, the impact of γ radiation on the absorbance, extinction coefficient, refractive index, optical dielectric parameters, optical conductivity and the nonlinear parameters of the NC films were investigated. Moreover, the changes in color between the irradiated samples and pristine were determined. The pristine NC film was colorless. It showed permanent color changes upon the γ irradiation. The induced modifications in the optical properties indicated that the prepared PVA/CMC/ZnS-NiO NC can be suitable candidate for the application of in optoelectronic devices.