Temperature and E-field-dependent polarization rotations in (211)-cut Pb(Mg1/3Nb2/3)0.69Ti0.31O3 (PMNT31%) single crystal

Abstract

Polarization rotations of temperature- and electric-field-dependent phase transformations in a (211)-cut Pb(Mg1∕3Nb2∕3)0.69Ti0.31O3Pb(Mg1∕3Nb2∕3)0.69Ti0.31O3 (PMNT31%) single crystal were observed by means of polarizing microscopy. Dielectric permittivity was also measured as a function of temperature and frequency. Below 380 K domains are mostly rhombohedral (R)(R) phase mixed with monoclinic (M)(M) domains. As temperature increases above 380 K, polarizations of the rhombohedral domains begin to rotate toward the cubic (C)(C) phase through monoclinic distortions, i.e., R→M→CR→M→C, associated with a long-range percolation of monoclinic phase near 380 K. However, the tetragonal phase was not observed apparently. Electric-field-dependent domain structures show that a long-range R→MR→Mphase transformation takes place in the range of 3–5kV∕cm3–5kV∕cm as electric field increases. The crystal cannot reach a monodomain as the electric field reaches 26kV∕cm26kV∕cm. A hysteresis loop of polarization versus electric field was also measured for comparison with electric-field-dependent observation of polarizing microscopy.