High energy storage capacity, heterogeneous domain structure and stabilization of intermediate phase in PbZrO₃-based antiferroelectric single crystals

Lead zirconate PbZrO₃ (PZ)-based antiferroelectric (AFE) materials have received tremendous attention due to their potential applications in high density energy storage capacitors. However, PZ suffers from an ultrahigh critical electric field (E_F), making it unsuitable for practical applications. To develop new materials with better energy storage performances, a bismuth-based perovskite, Bi(Zn_2/3Nb_1/3)O₃ (BZN) was introduced to PZ to form the PZ-BZN solid solution, and single crystals of this system were successfully grown from high temperature solution. The crystal structure, domain structure, and various physical properties of the crystals were investigated. The incorporation of BZN into PZ was found to stabilize the intermediate (IM) phase of rhombohedral symmetry existing between the AFE phase and the paraelectric (PE) phase. The origin of the IM phase was discussed. A heterogeneous ferroelastic/ferroelectric domain structure was found in the AFE phase of PZ-BZN, while a high domain wall density was observed in the IM phase. Most importantly, a significantly enhanced recoverable energy density was achieved together with improved dielectric permittivity and polarization in the PZ-BZN single crystals. This work unveils a novel single crystal material of high performance, potentially useful for energy storage applications, especially at mild temperatures, and provides a better understanding of the domain structure and the origin of the IM phase in PZ-based AFE materials, which will be beneficial to the design and synthesis of new AFE materials with better energy storage performances.