Intermediate phases in rhombohedral Pb(Mg1/3Nb2/3)1-xTixO3 crystal.

Phase transformations of (111)-cut Pb(Mg_1/3Nb_2/3)_1-xTi_xO₃ (x=0.30) single crystals before and after an electric (E)–field poling have been investigated by means of dielectric permittivity, hysteresis loop, polarization current, 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, an extra intermediate monoclinic (possible M_A) phase was induced and the crystal underwent an R-M_A-T-C phase sequence with significant responses in polarization current. The dielectric dispersion was diminished after poling and reappeared in the cubic state. The dielectric permittivities with and without a prior poling were found to follow the Curie–Weiss equation, [variant_greek_epsilon]^′=C/(T-T₀), above the Burns temperature 505 K with the same constants C=1.9×10⁵ K and T₀=460 K. [ABSTRACT FROM AUTHOR]