AC Conductivity and Dielectric Behaviour Analysis of PDMS Based Composites

Abstract

This study presents a comprehensive investigation of the AC conductivity and dielectric behaviour of PDMS-PZT composites over a wide frequency range. The electrical response of the material system exhibits strong frequency dependence, characteristic of disordered polymeric structures and heterogeneous composites. The AC conductivity analysis reveals a transition from frequency-independent DC conduction at low frequencies to dispersive AC conduction at higher frequencies, which is well described by Jonscher’s universal power law. The observed power-law exponent suggests that the dominant conduction mechanism is governed by correlated barrier hopping (CBH), indicating thermally activated charge carrier transport between localized states.
The dielectric properties of the system further support this conduction mechanism. The dielectric constant shows high values at low frequencies due to pronounced interfacial polarization arising from the Maxwell–Wagner–Sillars (MWS) effect, which originates from charge accumulation at interfaces with contrasting electrical properties. As the frequency increases, a gradual decrease in dielectric constant is observed due to the inability of dipolar and interfacial polarization mechanisms to follow the rapidly varying electric field.
The dielectric loss behaviour demonstrates significant energy dissipation at lower frequencies, primarily due to electrode polarization and charge carrier migration, while reduced losses at higher frequencies indicate improved dielectric stability. The presence of broad relaxation peaks confirms non-Debye type relaxation, suggesting a distribution of relaxation times within the material system. Furthermore, a strong correlation between AC conductivity and dielectric loss highlights the coupled nature of charge transport and polarization phenomena.
The incorporation of ceramic fillers such as PZT into the PDMS matrix enhances both conductivity and dielectric response by introducing additional interfacial regions and facilitating charge hopping pathways. Overall, the combined experimental and theoretical analysis provides valuable insights into the complex electrical behaviour of PDMS-based composites, making them promising candidates for applications in flexible electronics, capacitive sensors, and dielectric energy storage devices.