Enhanced energy storage performance of $${{\hbox {SrTiO}}}_3$$ SrTiO 3 modified Bi 0.5 Na 0.5 TiO 3 –BaTiO 3 –Bi 0.5 K 0.5 TiO 3 ceramics

Lead-free $$(1 - x)[0.884{\text{Bi}}_{{0.5}} {\text{Na}}_{{0.5}} {\text{TiO}}_{3} {-} 0.036{\text{BaTiO}}_{3} {-} 0.08{\text{Bi}}_{{0.5}} {\text{K}}_{{0.5}} {\text{TiO}}_{3} ] {-} x{\text{SrTiO}}_{3} ;0 < x \le 0.16$$ that is (1−x)[0.884BNT–0.036BT–0.08BKT]–xST ceramics are synthesized using conventional solid state reaction route. Structural analysis indicates the presence of rhombohedral–tetragonal Morphotropic Phase Boundary (MPB) in all prepared ceramics. Microstructural study reveal that ST acts as grain inhibitor. Polarization–Electric field and Strain–Electric field loop study indicate that increase of non-polar order with the increase of ST content. Relatively a large energy storage density of $$0.57\,{\hbox {J/cm}}^3$$ at 60 kV/cm obtained in the $${\textit{x}} = 0.08$$ ceramics, suggest that prepared ceramics are suitable for energy storage applications.