Enhanced energy storage properties in BNT-based ceramics with a morphotropic phase boundary modified by Sr(Mg1/3Nb2/3)O3

The development of dielectric capacitors for applications under medium-low fields is of great significance to the integration and miniaturization of electronic circuits. Lead-free piezoelectric ceramics based on the morphotropic phase boundary (MPB) compositions have made great progress in the past two decades. In this study, we selected an MPB composition of 0.8525BNT–0.10995BKT–0.03755BT (BBNKT) as the matrix and Sr(Mg1/3Nb2/3)O3 (SMN) as the end member to form relaxor ferroelectric ceramics for energy storage applications. We showed that 0.85BBNKT–0.15SMN ceramics exhibited a recoverable energy storage density Wrec of 3.53 J cm−3 and an efficiency η of 86.3% at a medium-low electric field of 310 kV cm−1. The ceramics also exhibited good thermal stability (25 °C–180 °C), frequency stability (1 Hz–100 Hz), and fatigue resistance (>105 cycles). The current study provided a new idea for the compositional design of energy storage ceramics by modifying the piezoelectric ceramics with MPB compositions into high-entropy relaxor ferroelectrics.