Effect of temperature and gamma irradiation on dielectric properties of FeGaInS ₄ /PVA composites

In this study, the effects of gamma radiation at various doses (500, 1500, and 2500 kGy) on nanocomposites synthesized by incorporating FeGaInS₄ layered semiconductor crystals into a PVA matrix at a concentration of 3 wt% were investigated. The aim of the research was to determine how radiation-induced structural and functional changes affect the dielectric and optical properties of the composite. The nanocomposites were synthesized using the solution casting method and analyzed before and after radiation using X-ray diffraction (XRD), UV-Vis spectroscopy, and dielectric spectroscopy techniques. XRD results indicated that at a lower radiation dose (500 kGy), cross-linking was predominant, leading to increased crystallinity. In contrast, at higher doses (1500 and 2500 kGy), chain scission became dominant, causing structural disorder and amorphization. UV-Vis analysis showed a decrease in absorption and an increase in transmittance. Moreover, the optical band gap (<i>E</i> _g) and Urbach energy (<i>E</i> _u) were found to be highly sensitive to the radiation dose. Dielectric measurements revealed that the highest values of the real part of permittivity (<i>ε</i>') and dielectric loss tangent (tg <i>δ</i>) were obtained at a radiation dose of 500 kGy, attributed to interfacial polarization and the formation of dipolar groups. The electrical conductivity followed the correlated barrier hopping (CBH) mechanism, with activation energy decreasing as the radiation dose increased. In conclusion, low-dose gamma radiation enhanced the structural stability and electro-optical performance of the nanocomposites, while higher doses led to degradation and a decline in functional properties. These findings underscore the practical significance of radiation-controlled material engineering.