Development of new polymer–BaTiO₃-composites with improved permittivity for embedded capacitors

A series of commercially available nanosized barium titanates has been investigated with respect to their use as high-k-ceramic filler in polymer based composites with improved dielectric properties. The thermal treatment of the barium titanate powders at 1,000°C causes a significant increase of the composite’s permittivity. X-ray diffraction experiments prior and after heat treatment revealed that the barium titanate with smallest particle size and the largest specific surface area possesses the thermodynamically unstable cubic phase. In case of the other investigated barium titanates the crystal lattice is distorted. Thermal treatment induces the phase change into the tetragonal one and crystal lattice relaxation enabling higher permittivity values. Composites with a solid load around 78 wt% with a bimodal particle size distribution show high permittivities around 50 and a low loss factor around 5‰ suitable for the realization of embedded capacitors via screen printing or tape casting.