Bridgman growth and electrical properties of Nd-doped PMN-PT single crystal with ultrahigh piezoelectricity

Using the polycrystalline material with a nominal composition of Nd0.01Pb0.985[(Mg1/3Nb2/3)(0.70)Ti-0.30]O-3, an Nd-doped PMN-PT single crystal has been grown successfully by a vertical Bridgman process. The perovskite structure and the crystalline phase evolution of the as-grown crystal were confirmed by X-ray diffraction analysis. A series of (001)-oriented crystal wafers, fabricated from different regions of the as-grown crystal boule, were characterized systematically to verify their electrical properties. Compared to the undoped PMN-PT single crystal, the crystal wafers under direct current polarization exhibited an improved piezoelectric coefficient d(33) of 1780-2870 pC N-1, along with a lower phase transition temperature T and a lower Curie temperature T-c in the range of 55-63 degrees C and 95-141 degrees C, respectively. The coercive field E-c and the remnant polarization P-r for the crystal wafers were measured to be 1.7-2.7 kV cm(-1) and 23.9-32.7 mu C cm(-2), respectively. It was found that the piezoelectric coefficient d(33) of the crystal wafer could be even elevated to the range 2200-3650 pC N-1 by applying alternating current polarization. The improved piezoelectricity for the crystal wafer under alternating current polarization may be associated with the increased domain density inside the crystal medium.