FIELD-INDUCED RELAXATION OF CRYSTAL-STRUCTURE IN DIPOLE-GLASS PHASE OF PMN-PT SINGLE-CRYSTAL - X-RAY STUDY

X-ray studies of the electric field-induced structural changes in 0.8P MN-0.2PT single crystal were made in the temperature range 300-400 K i ncluding the points of the supposed dipole-glass (T-DG approximate to 352 K) and ferroelectric (T-F approximate to 324) transitions. The cha nges in the form and intensities of the 005 and 224 reflexes were stud ied after the application the different electric fields (E < 5 x 10(5) V/m) along [001] cubic direction. At T > T-DG and T < T-F the instant aneous changes in the form and the intensity of the 224 reflex are in accordance with the cubic and rhombohedral symmetries of the parent an d ferroelectric phases correspondingly, while at T-F < T < T-DG the fi eld above some (temperature dependent) threshold value induces the sme aring of this Bragg peak followed by the slow (during 30-40 min.) form ation of the broad multiplet structure. Also the influence of the slow ac field (frequency 0.01 Hz) on the averaged over the period Bragg pe ak form was studied at 300 K < T < 400 K.