()PbMgNbOPbTiO₃,[100]-oriented relaxor ferroelectric crystals were studied by means of dielectric and acoustic emission methods in a temperature range up to 200C 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.

( )PbMg Nb O PbTiO ₃,[100] 取向弛豫铁电晶体通过介电和声发射方法在高达 200C 的温度范围和高达 1.2 kV/cm 的直流偏置电场下进行了研究。两种实验方法均成功检测到单斜-四方和四方-立方铁电相变。与四方-立方相变相关的介电常数最大值的偏置电场依赖性表现出 V 形效应，阈值为 0.5 kV/cm。相比之下，单斜四方相变温度的偏置电场依赖性没有表现出 V 形效应，但指出了 0.7 kV/cm 处的三临界点。这些结果并未证实所研究的晶体中存在临界终点。