Paper ID HP005 barium titanate-polymer composites produced via directional freezing

In this study we use a freeze casting technique to construct ceramic-polymer composites in which the two phases are arranged in an electrically parallel configuration. By doing so, the composites exhibit dielectric constant (K) up to two orders of magnitude higher than that of composites with ceramic particles randomly dispersed in a polymer matrix. In this technique, an aqueous ceramic slurry was frozen uni-directionally to form ice platelets and ceramic aggregates that were aligned in the temperature gradient direction. Upon freeze drying, the ice platelets sublimed and left the lamellar ceramic structure intact. The green ceramic body is fired to retain the microstructure and then the space between ceramic lamellae was infiltrated with a polymer material. The finished composites exhibit the high dielectric constant of ferroelectric ceramics while maintaining the flexibility and ease of post-processing handling of polymer materials. We also observed graceful failure behavior during dielectric breakdown testing.