Superior energy storage properties in lead-free Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics via compositional tailoring and bandgap engineering

Currently, lead-free ferroelectrics have been paid much attention due to their versatile applications, environmental friendliness and excellent energy storage properties (ESP). In this work, lead-free relaxor ferroelectrics (0.74-x)Na0.5Bi0.5TiO3-0.06BaTiO3-0.2SrTiO3-xBi(Mg0.5Zr0.5)O3 with superior ESP were successfully designed via compositional tailoring and bandgap engineering. A new peak was observed in the dielectric properties, corresponding to the phase transition from the R3c polar nano regions (PNRs) to the P4bm PNRs, which were consistent with the Rietveld refined XRD and TEM SAED analyses, in which superlattice spots for R3c and P4bm were observed. A recoverable energy storage density (Wrec) of 6.57 J/cm3 and an energy conversion efficiency of 88.6% were procured for ceramics with x = 0.16 at 355 kV/cm. Furthermore, a variation within 5% in Wrec was obtained over a wide temperature and frequency range. Moreover, a power density of 77.39 MW/cm3 and a discharge speed of 52.5 ns were also achieved at 180 kV/cm.