Fe-doping as a universal phase boundary shifter for BCZT ceramics across the morphotropic phase boundary

y mol% Fe-doped Ba(Zr0.2Ti0.8)O3—x mol%(Ba0.7Ca0.3)TiO3 (abbreviated as yFe:BCZTx) ferroelectric ceramics with y = 0, 0.375, 0.75, and 1.5 across the morphotropic phase boundary (MPB) with x = 44 and 56 were fabricated via conventional solid state reaction methods. Fe incorporated into the lattice and all the yFe:BCZTx ceramics showed pure perovskite structure. Fe-doping can significantly reduce the grain sizes and shift the tetragonal-cubic phase boundary toward lower temperature for all the investigated compositions across the MPB. A moderate enhancement of frequency dispersion on the dielectric constant was observed. The temperature dependent dielectric constant was analyzed according to modified Curie–Weiss law and the diffuse factor increased with increasing Fe-doping content. Relaxor-like slim polarization–electric field (P-E) loops were obtained for all BCZTx ceramics after Fe-doping. 1.5Fe:BCZTx ceramics shows almost hysteresis free P-E loops without obvious fatigue behavior after 10,000 cycles. The recoverable energy storage efficiency was significantly enhanced in 1.5Fe:BCZTx ceramics with good temperature stability. Our results indicate Fe-doping can be used as a universal phase boundary shifter and to increase energy storage efficiency for BCZT ceramics.