[101]‐Oriented Pb(Mg _1/3 Nb _2/3 )O ₃ –PbTiO ₃ Single Crystals Under Electric Loadings: Polarization Rotation Linking M _B , O , and R Phases

We report on the existence of monoclinic ( M _B ), orthohombic ( O ), and rhombohedral ( R ) phases in [101]‐oriented 74Pb(Mg _1/3 Nb _2/3 )O ₃ –26PbTiO ₃ (PMN–26PT) single crystals under electric loadings. Before electric loadings, the [101]‐oriented PMN–26PT single crystal is composed of R and monoclinic phases. Both M _B and R phases are revealed after being poled in the [101] direction. When the single crystal is subjected to bipolar cyclic electric field, an M _B phase bridges the reversal of domains of R phase. Reversal of the domains of M _B phase is achieved by either 180° domain switching or non‐180° domain switchings. Under static electric field, polarization rotation from R to M _B again occurs, and as the field increases, phase transition from M _B to O phase occurs. The O phase is metastable because it tends to change back to M _B phase after the removal of electric field. The findings are of importance for understanding the microstructure characteristics of [101]‐oriented PMN–PT single crystals that show the ultrahigh piezoelectric performances at the morphotropic phase boundary.