Enhanced antiferroelectric-like relaxor ferroelectric characteristic boosting energy storage performance of (Bi0.5Na0.5)TiO3-based ceramics via defect engineering

Lead-free (Bi0.5Na0.5)TiO3 (BNT)-based relaxor ferroelectric (RFE) ceramics have attracted a lot of attention due to their high power density and rapid charge-discharge capabilities, as well as their potential application in pulse power capacitors. However, because of the desire for smaller electronic devices, their energy storage performance (ESP) should be enhanced even further. We describe a defect engineering strategy for enhancing the antiferroelectric-like RFE feature of BNT-based ceramics by unequal substitution of rare-earth La3+ in this paper. The ESP of La3+-doped samples is raised by 25% with the same synthetic procedure and thickness, due to an increase in the critical electric field (E-field) and saturated E-field during polarization response, which is induced by a modification in the energy barrier between the lattice torsion. More impressively, an ultrahigh recoverable energy storage density Wrec of 8.58 J/cm3 and a high energy storage efficiency η of 94.5% are simultaneously attained in 3 at.% La3+-substituted 0.6(Bi0.5Na0.4K0.1)1-1.5xLaxTiO3-0.4[2/3SrTiO3-1/3Bi(Mg2/3Ni1/3)O3] RFE ceramics with good temperature stability (Wrec = 4.6 ± 0.2 J/cm3 and higher η of ≥90% from 30 °C to 120 °C), frequency stability, and fatigue resistance. The significant increase in ESP achieved through defect engineering not only proves the effectiveness of our strategy, but also presents a novel dielectric material with potential applications in pulse power capacitors.