Structural transformations in Pb(Mg1/3Nb2/3)(0.8)Ti0.2O3 single crystals in electric field

Phase transitions in single crystals of a ferroelectric-relaxor of the comp osition Pb(Mg1/3Nb2/3)(0.8)Tb0.2O3 in applied electric fields E ranging fro m 0 to 5 kV/cm have been studied by X-ray diffraction method. The evolution of the shape of the 224 refIection and the integrated intensity of the 005 reflections were studied in the field-cooled mode in the temperature range 290-430 K. Four temperature anomalies were established in the range of the fields used. It is concluded that, prior Co the formation of the rhombohed ral ferroelectric phase, the crystals exist in three inhomogeneous phases-e rgodic and nonergodic dipole glasses and a mixed phase with the coexisting ferroelectric and glassy regions. The mechanism of the effect of Ti+4 ions on the phase transition in the crystal are also discussed. (C) 2000 MAIK "N auka/Interperiodica".