Achieving excellent energy storage performances and eminent charging-discharging capability in donor (1-x)BT-x(BZN-Nb) relaxor ferroelectric ceramics

Prodigious efforts have been paid to explore excellent dielectric energy storage capacitors based on lead-free relaxor ferroelectric (RFE) ceramics in the last decades. However, there are rare candidates among them simultaneously possessing high energy storage density (Wrec), high efficiency (η), wide work temperature range and stable charge–discharge ability, etc. In this work, excellent energy storage performances are achieved in donor doped BaTiO3 (BT)-based RFE ceramics by adopting two effective strategies of domain engineering and defect engineering. By introducing Bi(Zn2/3-0.01xNb1/3+0.01x)O3+δ (BZN-Nb) into BT matrix, firstly, long-range ferroelectric polarization is broken to form polar nanoregions (PNRs) via domain engineering. Subsequently, Nb donor substitution results in a dramatic increase in bulk resistivity (ρb) accompanied by a significant increase in dielectric breakdown electric strength (EDBS) via defect engineering. Finally, a combination of relative high Pmax, much low Pr and giant EDBS ensures that the optimum composition x = 0.3 in (1-x)BT-x(BZN-Nb) system exhibits high Wrec of 5.96 J/cm3 and high η of 89.5 %. Such properties together with good thermal stability (up to 220 °C), good fatigue endurance (for 106 cycles) and eminent charging-discharging capability (e.g., discharge time t0.9 ∼ 50 ns, current density CD ∼ 1.17 kA/cm2 and power density PD ∼ 175.38 MW/cm3 at 300 kV/cm) suggest that the 0.7BT-0.3(BZN-Nb) ceramic is a very promising candidate among lead-free dielectric capacitors for energy storage applications.