Recent developments in transition temperature (Tc) perovskite crystals

This paper summarizes the temperature behavior of various relaxor-PT piezoelectric single crystals. Owing to the strongly curved morphotropic phase boundary (MPB), the usage temperature is limited by T_R-T, the rhombohedral to tetragonal phase transformation occuring at significantly lower temperatures than T_c. Attempts to modify the temperature usage range of PMN-PT and PZN-PT rhombohedral crystals using minor dopant modifications were limited, with little success of significant potential are crystals of PYN-PT, with a T_c>330°C, even though T_R-T was nearly half that value at ∼160°C. Lastly, single crystals in the novel Bi(Sc)O₃-PbTiO₃ system offer significantly higher T_cs>400°C, while exhibiting electromechanical coupling coefficients >90%.