An effective approach to achieve high energy storage density and efficiency in BNT-based ceramics by doping AgNbO3

摘要

Perovskite dielectric materials for capacitors have received wide attention in recent years because of their fast charge/discharge rates and high power densities. In this work, lead-free relaxor ferroelectric ceramics of (1 - x)[(Bi0.55Na0.45)(0.94)Ba-0.06](0.98)La0.02TiO3-xAgNbO(3) were synthesized by a conventional sintering method. All ceramics are situated at the morphotropic phase boundary (MPB) of rhombohedral and tetragonal phases, suggesting that a small amount of AgNbO3 (abbreviated as AN) doping does not affect this phase-coexistence structure. The added AN not only improves the dielectric breakdown strength (DBS) from 84.11 kV cm(-1) (x = 0) to 137.89 kV cm(-1) (x = 0.01), but also broadens the phase transition peak and enhances the relaxation behavior of ceramics. Moreover, when x = 0.01, the ceramic demonstrates a high saturation polarization (P-s) of 25.54 mu C cm(-2) and a low remanent polarization (P-r) of 0.65 mu C cm(-2) at an electric field of 130 kV cm(-1). More importantly, an optimal energy storage density (W-s) of 1.697 J cm(-3) and energy efficiency (eta) of 82.3% are simultaneously achieved in the BNBLT-0.01AN ceramic with excellent thermal stability (similar to 25-175 degrees C) and frequency stability (similar to 10-80 Hz).