Synchrotron radiation analyses of lattice strain behaviors for rhombohedral Pb(Zn1/3Nb2/3)O₃–PbTiO₃ single crystals under electric fields

The behaviors of intrinsic unit-cell strains under applied electric fields (E) along the 〈100〉 direction were investigated for rhombohedral Pb(Zn1/3Nb2/3)O3–(6–7%)PbTiO3 (PZN–PT) single crystals by in-situ high-energy synchrotron radiation X-ray diffraction study. The E-induced unit-cell strains accompanied with a reversible phase transition from rhombohedral to tetragonal via two monoclinic phases agree well with the macroscopic strain properties observed for the crystals. The structural analyses using the single-crystal X-ray diffraction and domain observations with piezoresponse force microscopy lead to a conclusion that the E-induced unit-cell strains are mainly responsible for the high piezoelectric performance of the PZN–(6–7%)PT single crystals.