Bi(Mg0.5Ti0.5)O3 addition induced high recoverable energy-storage density and excellent electrical properties in lead-free Na0.5Bi0.5TiO3-based thick films

(1-x)Na0.5Bi0.5TiO3-xBi(Mg0.5Ti0.5)O3 (NBT-BMT) thick films were designed for achieving large recoverable energy-storage density (Wrec). A large Wrec of 40.4 J/cm3 was detected in the thick film for x = 0.4, which was more than 4 times larger than that of the pure NBT film. The addition of BMT induced slim polarization hysteresis (P-E) loops at room temperature. The slim P-E loops improved the difference between the maximum polarization (Pmax) and the remnant polarization (Pr). Besides, a breakdown strength field (BDS) of 2440 kV/cm was also detected in the thick film for x = 0.4. The high BDS was caused by the reduced leakage current density. Furthermore, the thick film for x = 0.4 possessed superior energy-storage stability under different temperature, frequency and electric-field cycling. In addition, 90% of the pulsed discharge energy density could be released in less than 1100 ns by using a pulsed discharge measurement.