Stress and temperature-induced phase transitions and thermal expansion in (001)-cut PMN-31PT single crystal

Phase transitions and thermal-expansion behavior were investigated in (001)(-cut) 0.69Pb(Mg1/3Nb2/3) O-3-0.31PbTiO(3) (PMN-31PT) single crystals under different stress and temperature conditions. At room temperature, moderate stress is found to induce monoclinic (M-A) -> rhombohedral (R) transition, whereas high stress promotes rhombohedral (R) -> orthorhombic (O) transition. The transition behavior of the sample during heating is considerably more complex than during cooling. These transitions are associated with a change in local symmetry based on a model of stress-induced polarization rotation. Thermal expansion behavior of the sample strongly depends on stress. Under 14 MPa, the sample displays linear-contraction behavior, and a large contraction coefficient alpha = -17 x 10(-6) K-1 is obtained within a wide temperature range (from room temperature to 110 degrees C). (C) 2015 Elsevier B.V. All rights reserved.