Revisiting the Dielectric Breakdown in a Polycrystalline Ferroelectric: A Phase‐Field Simulation Study

Abstract

To understand the dielectric breakdown in a polycrystalline ferroelectric, a thorough phase field simulation has been performed by introducing a new degradation function. Time and position evolution of breakdown path, electric field dependence of breakdown time, and the effect of several parameters such as grain orientation, dielectric constant of grain and grain‐boundaries (GBs), thickness of GBs (dGB${d}_{\text{GB}}$), and grain size (Gnormala${G}_{\text{a}}$) on the threshold breakdown electric field, EBT${E}_{\text{BT}}$, are investigated. The results indicate that EBT${E}_{\text{BT}}$ is improved with decreasing dielectric constant. The dependence of EBT${E}_{\text{BT}}$ on grain size and GB's thickness obeys a power function Gnormala−n${G}_{\text{a}}^{-n}$ (n=0.42$n=0.42$) and dGBn${d}_{\text{GB}}^{n}$ (n=0.3$n=0.3$), respectively. The results help to engineer the grains and GBs properties and achieve a high breakdown electric field, which is very important in energy‐storage applications.