Phase Field Simulation of Dielectric Breakdown in Ferroelectric Composites

The ferroelectric composite material with ferroelectric polymer as the matrix and ferroelectric ceramic as the filler overcomes the inverted relationship between high polarization strength and high breakdown strength of single-phase ferroelectric materials, exhibits excellent multi-field coupling properties such as piezoelectricity and energy storage. Recently, it draws increasing attention. However, the stress and electric field concentration at the interface of ferroelectric composite materials can cause the electromechanical coupling failure of the materials, and the dielectric breakdown is one of the main failure modes of ferroelectric composite materials. Therefore, understanding the effects of ceramic fillers on the dielectric breakdown performances of ferroelectric composite materials is crucial for their application in high-performance energy conversion and storage devices. Aimed at the multi-field coupling failure of ferroelectric composite materials, a phase field model involving polarization, strain, and breakdown order parameters was established to study the dielectric breakdown behavior of ferroelectric composite materials under electrical loads. The phase field simulation results indicate that, as the particle size of the ceramic filler increases, the electrical breakdown path will avoid the ceramic particles, and the maximum electric field inside the material will gradually increase, resulting in a lower breakdown strength of the composite material. In addition, a nonlinear relationship exists between the dielectric breakdown strength and the particle size of the filler. The work provides a certain theoretical basis for the design of dielectric breakdown strength of ferroelectric composite materials.