Poling field versus piezoelectric property for [001]_c oriented 91%Pb(Zn_1/3Nb_2/3)O₃-9%PbTiO₃ single crystals

Electromechanical property measurements and microstructure observations using optical microscopy were performed on a [001]_c oriented k ₃₃ resonator made of 91%Pb(Zn_1/3Nb_2/3)O ₃-9%PbTiO₃ single crystal, which was polarized under different electric fields. At room temperature, when the poling field is 1100 V/mm, the electromechanical coupling factor k₃₃ is 0.90 and piezoelectric coefficient d₃₃ is 1665 pC/N. Such superior electromechanical properties could be attributed to the formation of monoclinic multi-domain structure, which transforms to tetragonal phase at 46 °C. While at a higher poling field of 1200 V/mm, the crystal becomes singledomain tetragonal state and its k₃₃ and d₃₃ are only about 0.69 and 850 pC/N, respectively. The critical poling field to transform the monoclinic phase to the tetragonal phase is found to be ∼1120 V/mm.