Barium titanate/polydimethylsiloxane nano/microcomposites fabrication, morphology, dielectric response and functionality

Abstract

Polymer matrix composites with embedded ferroelectric and/or piezoelectric particles, constitute a novel and interesting class of engineering materials. The incorporation of ferroelectric and/or piezoelectric particles within a polymer matrix is expected to add functionality to the resulting composite, due to the variation of polarisation of the ceramic particles with temperature. In this work, an elastomeric matrix such as polydimethylsiloxane and BaTiO₃ nano and microparticles were used for the fabrication of composites at various concentrations and sizes of the reinforcing phase. Morphological and structural characteristics were investigated via scanning electron microscopy images and X-ray diffraction patterns. The dielectric behaviour of all fabricated specimens was investigated via broadband dielectric spectroscopy, in a wide frequency (10⁻¹ Hz–10 MHz) and temperature (30–200°C) range. In the dielectric spectra, two relaxation processes were detected, namely cold crystallisation and interfacial polarisation. Values of dielectric permittivity enhance with filler content, and particles’ size, while diminishes significantly with frequency. Finally, the ability of the prepared systems to store energy was examined by calculating their energy density. The higher energy-storing efficiency is exhibited by the micro-BaTiO₃ reinforced composites, while functional behaviour is induced via the thermally activated structural changes of ferroelectric particles.