Effect of temperature and AC field duration on the dielectric behavior of PVA/GO/FeGaInS4 nanocomposites

Abstract

This study explores the dielectric behavior of polyvinyl alcohol (PVA)-based nanocomposites incorporating 2 wt% FeGaInS₄ and 3 wt% graphene oxide (GO), focusing on the effects of temperature and alternating current (AC) electric field exposure duration. The nanocomposites were synthesized via ultrasonic dispersion in water, followed by casting and ambient drying. X-ray diffraction (XRD) confirmed the preservation of the FeGaInS₄ crystalline phase and the disordered, exfoliated state of GO within the polymer matrix. Dielectric spectroscopy, performed across 120 Hz to 1 MHz and temperatures between 40 and 80 °C, revealed a decrease in dielectric constant (ε′) with frequency, attributed to interfacial and dipolar polarization mechanisms. With increasing temperature, ε′ rose due to enhanced chain mobility and interfacial polarization. Notably, 2 h of AC field exposure at 40 °C improved both ε′ and dielectric loss (tan δ), while prolonged exposure led to relaxation effects and reduced performance. Activation energy (E_a), calculated using the correlated barrier hopping (CBH) model, decreased from 0.75 to 0.40 eV at 500 Hz with longer field exposure, indicating improved charge hopping. At higher frequencies (50 kHz), E_a showed a transient increase before stabilization. The results demonstrate the tunability of dielectric properties via AC field treatment, highlighting the potential of these nanocomposites for applications in flexible electronics and dielectric energy storage.