Influence of Gamma irradiation on the structural and optical characteristics of Li ion-doped PVA/PVP solid polymer electrolytes

Abstract

Lithium ions-doped polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) films were prepared by solution casting technique and exposed to 100 kGy gamma radiation. The structural modifications in the samples before and after irradiation were studied using X-ray diffraction XRD and UV–Vis spectroscopy. The results indicated that absorbance A ðkÞ and absorption index (k) increased, while semicrystalline nature of the blend decreased due to the addition of Li2SO4 and irradiation. The optical band gap Eopt g of the composites showed significant decrease from 2.98 to 2.196 eV by adding Li2SO4 and from 2.83 to 2.08 eV after irradiation due to cross-linking. The Tauc’s relation indicated that allowed transitions are indirect for both irradiated and unirradiated samples. The Urbach energy (Eu) increased with increasing Li ion content and exposure to c irradiation. The dependence of dielectric permittivity e1, dielectric loss e2 and optical conductivity ropt on photon energy hm was also studied.