Effect of chemical inhomogeneity on domains and ferroelectric properties of Fe‐modified 0.77Bi 0.5 Na 0.5 TiO 3 –0.23SrTiO 3

Lead‐free 0.77(Bi 0.5 Na 0.5 )TiO 3 –0.23Sr(Ti 1− x Fe x )O 3 ( x = 0, 0.04) ( BNT –23 STF x ) was prepared using a conventional solid‐state reaction route. The effects of Fe‐modification on the chemical homogeneity from a μm scale perspective, the core‐shell domains structures, and the ferroelectric properties were investigated. The chemical homogeneity was analyzed using energy dispersive X‐ray mapping in scanning transmission electron microscopy mode, and the field‐dependent behaviors of strain and polarization were obtained to determine the ferroelectric properties. Substituting Fe 3+ for Ti 4+ resulted in completely different electrical behavior and properties, despite similar XRD patterns and microstructures. The Fe‐substitution promoted the mobility of Sr 2+ ions in the BNT phase and, as a consequence, the chemical homogeneity increased and the core‐domains collapsed. Extending the ceramic processing, such as milling time and sintering time, affected domain distribution and compositional inhomogeneity, which led to a gradual transformation from ferroelectric to relaxor.