Non-linear ferroelectric composite dielectric materials

The use of ferroelectric fillers in polymers can allow the formulation of a composite material which possesses enhanced AC currents at elevated electrical field strengths. This non-linear characteristic can be utilised as a stress relieving mechanism in applications with non-uniform electric fields. The enhanced characteristics are achieved through electrical field dependent permittivity mechanisms, which are occurring within the composite material. These stress relieving materials have distinct advantages over previous stress relieving polymer composites, using conductive or semi-conductive fillers, however, stress relief is only realisable under AC fields. The ferroelectric material used in these investigations is barium titanate, which has been used as a filler in an acrylic base resin system. The experimental results show how both the AC and DC conductivities are influenced by the electrical field strength, at a variety of filler concentrations. The research has also looked into how the AC and DC characteristics change as the degree of cure of the resin system is increased and how the particle size of the barium titanate influences the behaviour of the material.