Critical character of the field dependence of giant values of converse piezoelectric moduli in textured 0.675Pb(Mg 1/3 Nb 2/3 )O 3 –0.325PbTiO 3 ceramics

Temperature and field dependences of dielectric permittivity ε and unipolar electric field-induced strain S of the textured 0.675Pb(Mg1/3Nb2/3)O3−0.325PbTiO3 ceramics have been studied in the 25 °C … 200 °C range. Temperature dependences of both dielectric permittivity and converse piezoelectric modulus d*33 show anomalies corresponding to phase transitions between rhombohedral (monoclinic), tetragonal and cubic phases. Based on the data of dielectric and field-induced strain studies, the E,T-phase diagram is plotted. The possible critical behavior of converse piezoelectric modulus d*33 and its correlation with the position of the known critical point in the E,T-phase diagram of PMN-xPT system is discussed.