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)(0.70)Ti0.30O3 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, epsilon'=C/(T-T-0), above the Burns temperature 505 K with the same constants C=1.43 x 10(5) K and T-0=462 K. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3009319]