Ge, Wenwei; Luo, Chengtao; Zhang, Qinhui; Devreugd, Christopher P.; Ren, Yang; Li, Jiefang; Luo, Haosu; Viehland, Dwight D. (American Institute of Physics, 2012-05-01)
The dielectric, ferroelectric, and electric field-induced strain response of [001]-and [101]-oriented 0.944Na(0.5)Bi(0.5)TiO(3)-0.056BaTiO(3) (0.944NBT-0.056BT) single crystals were investigated as a function of temperature and dc bias (E). An ultrahigh electromechanical response with large amplitude longitudinal piezoelectric coefficients as high as d(33)=2500 pm/V was found in [001](PC) oriented 0.944NBT-0.056BT single crystals near a depolarization temperature of T-d = 130 degrees C. In-situ XRD revealed that the enhanced piezoelectric properties resulted from a polarization extension between a polar pseudocubic phase with a slight tetragonal (P4bm) distortion and a polar tetragonal one with a large tetragonal distortion of c/a = 1.02. Our findings indicate a potential approach to high performance lead-free piezoelectrics, via polarization extension. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4709619]