Excellent energy storage and discharge performances in Na1/2Bi1/2TiO3-based ergodic relaxors by enlarging the [AO(12)] cages

In this work, a lead-free 0.86(0.93Na(1/2)Bi(1/2)TiO(3)-0.07BaTiO(3))-0.14K(1/2)Bi(1/2)(Zn1/3Nb2/3)O-3 (KBZN14) ergodic relaxor demonstrates excellent energy storage performance: W-s = 6.48 J cm(-3), W-r = 5.10 J cm(-3), and eta = 80% at a moderate field of 29.0 kV mm(-1), accompanied by an outstanding frequency and temperature stability as well as a fast discharge rate t(0.9) of 69-79 ns. The excellent energy storage performance of the sample KBZN14 originates from the synergic effect of KBZN introduction: the enlargement of the [AO(12)] cages of the pseudocubic perovskite host to facilitate the local polarization, and the complex cations (Zn1/3Nb2/3)(4+) destroy the long-range correlations to percolate the polar nanoregions (PNRs) to room temperature. Our work provides a way to design NBT-based materials as a candidate for high energy density and pulse capacitor applications.