Fabrication and characterization of composites of a perovskite and polymers with high dielectric permittivity

Abstract

Composites of strontium titanate (SrTiO3) at loadings up to 50 vol.% with polar poly(butylene terephthalate) (PBT) and non-polar linear low density polyethylene (LLDPE) were prepared to investigate their dielectric responses in the wireless frequency range. The SrTiO3 particles were uniformly dispersed in the polymers at low loadings, but were more bead-like and agglomerated at higher SrTiO3 loadings. The SrTiO3 has a strong nucleating effect on both polymers, increasing the crystallization temperature and reducing the crystallinity of both polymers. Dielectric properties of composites were measured between 2.45−5 GHz. Dielectric permittivity (ε') of composites at 2.45 GHz increased with increasing SrTiO3 content. ε' increased by a factor of 5 for PBT, from 3.7 for unfilled PBT to 16.5 and by a factor of ∼8.5 for unfilled LLDPE, from 2.3 to 19.7 for maximum SrTiO3 loading. The composites had similar dissipation factor values as the unfilled polymers. The Lichtenecker model was in good agreement with the experimental data.