Improved dielectric, ferroelectric and energy storage properties of (Sr0.55Bi0.3)(Ni1/3Nb2/3)O3 modified NaNbO3 ceramics via phase modulation and relaxation enhancement

Antiferroelectric NaNbO3 ceramics are potential candidates for pulsed power applications, but their energy efficiency and energy densities are low owing to the irreversible transition of NaNbO3 from antiferroelectric to electric field-induced ferroelectric phases. (Sr0.55Bi0.3)(Ni1/3Nb2/3)O3 was doped into NaNbO3 ceramics to modify their dielectric and ferroelectric properties for improvement of the energy-storage properties of NaNbO3 ceramics. When the doping content is small, the electric field for induction of phase transition was delayed due to the decreased tolerant factor of modified NaNbO3 ceramics. When the doping content was between 10 and 15 mol%, a structural phase transition from orthorhombic to tetragonal occurred in NaNbO3-based ceramics. Thus, the synthesized paraelectric phase effectively decreased the polarization hysteresis and increased the dielectric constant at room temperature, which benefits better energy-storage performances. Besides, local lattice stress resulting from the effect of multiple-element doping reduced domain sizes and promoted domain reversibility to improve energy efficiency. Consequently, recoverable energy storage of 0.818 J/cm3 and energy efficiency of 85.3% were achieved in 0.85NaNbO3–0.15(Sr0.55Bi0.3)(Ni1/3Nb2/3)O3 ceramics under 160 kV/cm. Consequently, this study offers a feasible approach to improve the application of NaNbO3 in the field of energy storage.