Energy storage properties under moderate electric fields in BiFeO3-based lead-free relaxor ferroelectric ceramics

Abstract

Achieving high overall energy-storage properties under moderate electric fields is of great significance for practical applications of energy-storage ceramic capacitors. In this work, an ultrahigh recoverable energy-storage density (Wrec) of ∼ 3.9 J/cm3 and a high energy-storage efficiency (η) of ∼ 80% are simultaneously achieved under a moderate electric field of 25 kV/mm in a new ternary lead-free relaxor ferroelectric (FE) ceramic of 1 wt.%Nb2O5-doped 0.46Bi1.02FeO3-0.29BaTiO3-0.25Bi0.5Na0.5TiO3 (BF-BT-BNT). Together with excellent thermal and frequency stability of Wrec = 1.68 ± 12%J/cm3, η = 90 ± 9%, 0.1–100 Hz; Wrec = 1.61 ± 6%J/cm3, η = 87 ± 5% within 30–170 °C, a large power density of PD ∼ 43.0 MW/cm3 and a fast discharge rate of t0.9 ∼ 45 ns, Nb2O5-doped BF-BT-BNT ceramics exhibit promising potentials for environment-friendly advanced pulsed power capacitors. Multiscale structure characterization reveals that the incorporation of Nb2O5 into BF-BT-BNT significantly increases the local structure disorder, leading to a heterogeneous nanodomain morphology. This makes the Nb2O5-doped BF-BT-BNT ceramic maintain a high maximum polarization, but obviously suppressed polarization hysteresis, thus responsible for significantly improved overall energy-storage properties.