On the question of the critical end point in the (1 − x)PbMg_1/3Nb_2/3O₃-xPbTiO₃ relaxor ferroelectric single crystals based on acoustic emission data studies

Abstract

( )PbMg Nb O PbTiO3, [100]-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.

Non-trivial Behavior of Temperature of Dielectric Constant Maximum in (Pb/La)(Zr/Ti)O3 9/65/35 Relaxor Ferroelectric Ceramics Detected by Acoustic Emission

“…Figure 1 presents the T-E phase diagram of behavior of T m in 9/65/35 PLZT as well as the behavior of T c in the same compound reconstructed from Ref 6 . It is clearly seen that the T m , detected by AE, in dependence on E exhibits a V-shape, as it would be expected, lying fully within ER phrase as previously observed in PMN-0.30PT 5 .The E th is found to be 1.15 kV/cm, that is approximately the same as in both PMN-0.24PT 1 and PFN-0.02PT 10 . Because the E th is equivalent to RFs in the RFEs, it is means that the 0.09 mol.…”

“…It is need to stress that the piezomodule maximum occurs in the vicinity of V-shape 3 , that might be used in applications. Meanwhile, recently it was shown that the T m (E) V-shape fully lies within the ER phase in 0.70PMN-0.30PT crystals when applying the acoustic emission (AE) 5 . This is due to sharp bursts of AE in comparison with smeared dielectric maximum.…”