Is there a spontaneous ferroelectric phase transition in 0.83PbMg1/3Nb2/3O3-0.17PbTiO3 single crystal?

The macroscopic response of 0.83PbMg(1/3)Nb(2/3)O(3)-0.17PbTiO(3) (PMN-17PT) single crystals has been investigated in order to resolve existing controversy about the structural phase transition in the rhombohedral side of (1-x)PbMg1/3Nb2/3O3-xPbTiO(3) phase diagram. The combination of nonlinear dielectric spectroscopy, temperature dependant polarization and strain hysteresis loop measurements and ultrasonic spectroscopy revealed that ferroelectric phase occurs spontaneously in PMN-17PT single crystals. The experimental techniques applied in this work probe the bulk of the sample and can unambigously determine the existence of a spontaneous ferroelectric phase. The experiments showed that zero-field cooled sample has a normal ferroelectric hysteresis loop at room temperature. The electric-field dependence of induced polarization revealed that at a certain electric field the sample undergoes transformation from polydomain to monodomain-like states. The 1 st order phase transition at 330 K was evidenced by the third order nonlinear dielectric susceptibility for monodomain sample. The nonlinear dielectric response of an unpoled sample does not show such abrupt jump and is more similar to the response of canonical relaxor PbMg1/3Nb2/3O3. Zero-field heating and zero-field cooling experiments also revealed very slow domain formation processes appearing at 300-320 K temperature. They are affected by the experimental conditions. There are evidences that on cooling the domains tend to grow in the sample. (C) 2018 Elsevier B.V. All rights reserved.