- (1 - x)PbMg1/3Nb2/3O3-xPbTiO3, -oriented relaxor ferroelectric crystals were studied by means of dielectric and acoustic emission methods in a temperature range up to 200 °C and under a dc bias electric field up to 1.2 kV/cm. The monoclinic-tetragonal and tetragonal-cubic ferroelectric phase transitions were successfully detected by both experimental methods. The bias electric field dependence of the temperature of a dielectric constant maximum, related to tetragonal-cubic phase transitions, exhibits a V-shape effect with a threshold field of 0.5 kV/cm. In contrast, the bias electric field dependence of the temperature of a monoclinic-tetragonal phase transition exhibits no V-shape effect but points out a tricritical point at 0.7 kV/cm. These results have not confirmed the existence of the critical end point in the crystals under studies.
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