Vortex domain configuration for energy-storage ferroelectric ceramics design: A phase-field simulation
Ziming Cai, Chaoqiong Zhu, Longwen Wu, Bing Luo, Peizhong Feng, Xiaohui Wang
Abstract
The utilization of ferroelectrics in forms of ceramics, films, and composites toward energy-storage applications is of great interest recent years. However, the simultaneous achievement of high polarization, high breakdown strength, low energy loss, and weakly nonlinear polarization–electric field (P–E) correlation has been a huge challenge, which impedes progress in energy storage performance. In this work, a vortex domain engineering constructed via the core–shell structure in ferroelectric ceramics is proposed. The formation and the switching characteristics of vortex domains (VDs) were validated through a phase-field simulation based on the time-dependent Ginzburg–Landau kinetic equation. Benefiting from the smaller depth of a potential well in the energy profiles, the switching of VDs was much easier than that of conventional large-sized domains, which was found to be the origin of the lower coercive field, lower remanent polarization, and weaker nonlinear P–E correlation. Choosing BaTiO3 (BT) as a representative of ferroelectric ceramics, the shell fractions and permittivity values were varied in our phase-field simulation to optimize the energy storage performance. As a result, a large discharge energy of 6.5 J/cm3 was obtained in BT ferroelectric ceramics with a shell fraction of 5% and a shell permittivity of 20 under the applied electric field of 100 kV/mm, which is almost 140% higher than that with no shell structure. In general, the vortex domain engineering proposed in this work can serve as a universal method in designing high-performance ferroelectrics with simultaneous high breakdown strength, high discharge energy density, and high energy efficiency.