Simultaneous enhancement in energy storage density and efficiency in (Sr,Ba)Nb2O6-based relaxor ferroelectric ceramics

The development of ceramic capacitors that deliver excellent recoverable energy density (Wrec) and high efficiency (η) has been attracting significant attention recently due to the growing need in electronic industry. Herein, a relaxor ferroelectric ceramic with a tetragonal tungsten bronze structure is designed based on Sr0.6Ba0.4Nb2O6, which simultaneously shows a notable Wrec of 5.1 J/cm3 and an excellent η of 89.4% under 500 kV/cm after incorporating 10 mol. % perovskite end-member Bi(Zn0.5Ti0.5)O3. This is attributed to the reduced grain size, enhanced dielectric relaxation characteristics, and emergence of a superparaelectric phase with weakly coupled polar nanoregions. Furthermore, this ceramic sample also exhibits excellent frequency and thermal stability, exceptional fatigue endurance, and good charging–discharging behaviors. This study supplies an attractive candidate with a tungsten bronze structure for advanced capacitive energy-storage applications.