Field-induced intermediate orthorhombic phase in (110)-cut Pb(Mg1/3Nb2/3)0.70Ti0.30O3 single crystal

Phase transformations of (110)-cut Pb(Mg1/3Nb2/3)0.70Ti0.30O3 single crystal before and after an electric (E)-field poling have been investigated by means of dielectric permittivity, polarization current, hysteresis loop, and in situ x-ray diffraction as a function of temperature. An R-T-C transition sequence was observed in the unpoled sample upon zero-field heating. R, T, and C are rhombohedral, tetragonal, and cubic phases, respectively. After a prior E-field poling, the crystal underwent an R-O(R)-T-C phase sequence with significant responses in polarization current. O(R) represents that the minor R phase coexists in the orthorhombic matrix. The dielectric permittivities with and without a prior poling were found to follow the Curie–Weiss equation, ε′=C/(T−T0), above the Burns temperature 505 K with the same constants C=1.43×105 K and T0=462 K.