Enhanced energy storage properties in BNT-based ceramics with a morphotropic phase boundary modified by Sr(MgNb)O

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(Mg 1/3 Nb 2/3 )O 3 (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 W rec 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 (>10 5 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. The development of dielectric capacitors for applications under medium-low fields is of great significance to the integration and miniaturization of electronic circuits.