Excellent Energy-Storage Properties Achieved in BaTiO₃-Based Lead-Free Relaxor Ferroelectric Ceramics via Domain Engineering on the Nanoscale

Abstract

Barium titanate-based energy-storage dielectric ceramics have attracted great attention due to their environmental friendliness and outstanding ferroelectric properties. Here, we demonstrate that a recoverable energy density of 2.51 J cm^-3 and a giant energy efficiency of 86.89% can be simultaneously achieved in 0.92BaTiO₃-0.08K_0.73Bi_0.09NbO₃ ceramics. In addition, excellent thermal stability (25-100 °C) and superior frequency stability (1-100 Hz) have been obtained under 180 kV cm^-1. The first-order reversal curve method and transmission electron microscopy measurement show that the introduction of K_0.73Bi_0.09NbO₃ makes ferroelectric domains to transform into highly dynamic polar nanoregions (PNRs), leading to the concurrently enhanced energy-storage properties by the transition from ferroelectric to relaxor ferroelectric (RFE). Furthermore, it is confirmed by piezoresponse force microscopy that the appearance of PNRs breaks the long-range order to some extent and reduces the stability of the microstructure, which explains the excellent energy-storage performance of RFE ceramics. Therefore, this work has promoted the practical application ability of BaTiO₃-based energy-storage dielectric ceramics.