Obtaining Greatly Improved Dielectric Constant in BaTiO 3 -Epoxy Composites with Low Ceramic Volume Fraction by Enhancing the Connectivity of Ceramic Phase.

Ceramic-polymer dielectric composites show promising potential as embedded capacitors, whereas it is a great challenge to obtain a high dielectric constant (ε r ) at a low ceramic volume fraction ( V c ). This work demonstrates a strategy for overcoming this challange. By employing a high sintering temperature ( T s ) and introducing porogen, BaTiO 3 ceramics with both great connectivity and high porosity are obtained, and the composites with improved ε r at a low V c are prepared after curing the epoxy monomer, which is infiltrated into the porous ceramic bodies. For the composite with a T s of 1300 °C and a V c of 38.1%, the ε r is as high as 466.8 at 1 kHz, which is improved by about nine times compared to the 0-3 counterpart with a higher V c of 60.8%. Furthermore, the composite exhibits low dielectric loss and good frequency and temperature stability of ε r , indicating the great potential for practical applications. Finite element simulation shows that the enhanced connectivity of BaTiO 3 increases the electric field intensity in high-ε r BaTiO 3 dramatically and therefore plays a key role in the dielectric response of the composite. This work not only sheds light on the high-ε r ceramic-polymer composites but also deepens the understanding on the relationship between their properties and microstructures.