A high QM relaxor ferroelectric single crystal: Growth and characterization

Mn doped PIN-PMN-PT single crystals with diameter of 50mm have been successfully grown by the Bridgman method along <;111>;, <;110>; and <;001>; orientations. The effect of the acceptor dopant, Mn, on mechanical loss and other electromechanical properties was studied in comparison with pure PIN-PMN-PT single crystal under high and low electric fields. A complete set of piezoelectric, dielectric and elastic properties was derived from resonance measurements. It was demonstrated that by doping Mn, Q_M increases 4-5 times to 700-1000 in <;001>;-poled longitudinal samples without any compromise in electromechanical coupling (k33). Mn doped PIN-PMN-PT crystals also show strong anisotropy. For <;110>; poled longitudinal samples, Q_M and Ec increase to above 1000 and 8-10kV/cm, respectively, which is comparable to "hard" PZT ceramics. The fatigue behavior was investigated as function of crystal orientation and magnitude of the electric field. Polarization degradation was observed to suddenly occur along <;110>; orientation above 100 cycles of 15kV/cm bipolar field, while nearly no fatigue was seen along <;001>; orientation.