Transformation Toughening in Solid Dielectrics

High breakdown-resistant solid dielectrics are necessary in almost all kinds of dielectric systems, such as dielectric energy-storage devices, piezoelectric actuators, electrocaloric devices, and dielectric capacitors. However, the low breakdown strength of solid dielectrics, especially ceramic dielectrics, is the main obstacle limiting their practical applications. Inspired by the transformation toughening in brittle materials, an approach to enhance the breakdown strength of solid dielectrics is proposed in this work, and the internal mechanism is studied via a phase-field breakdown model. Simulation results indicate that the phase transformation has a significant effect on the dielectric breakdown strength, especially when the critical electric fields for the phase transformation and breakdown are comparable. Compared to dielectrics without phase transformation, the dielectric breakdown strength is nearly doubled when the phase transformation occurs during the breakdown process. Therefore, a reasonable design of phase-transformed dielectrics is expected to be an effective way to achieve the high breakdown resistance.