Electromechanical strain in Bi(Zn1/2Ti1/2)O3-(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3 solid solutions

Solid solutions ceramics of the Bi(Zn0.5Ti0.5)O-3-(Bi0.5K0.5)TiO3-(Bi0.5Na0.5)TiO3 ternary system for <20 mol. % BZT were created and confirmed to be single phase using x-ray diffraction. The dielectric dispersion showed decreasing T-max of the dielectric spectrum with a broadening of the transition with increasing BZT content. At 2.5BZT-40BKT-57.5BNT, a secondary transition commonly observed for morphotropic phase boundary (MPB) BNT-BKT was observed. The ferroelectric behavior of the system was characterized by a transition where the polarization hysteresis showed a severe pinching effect on remanent polarization (20.8 mu C/cm(2) at 2.5% BZT) as BZT contents was increased (P-r = 2.3 mu C/cm(2) at 20% BZT). Similarly, as the temperature increased to 175 degrees C, the remanent polarization of the 2.5% BZT composition significantly reduced to 2.1 mu C/cm(2). The onset of this transition corresponds to the lower temperature frequency dispersion observed in the dielectric spectrum. The strain hysteresis experienced analogous transition to the polarization, with a change in shape from typical ferroelectric butterfly to a complete loss of negative strain as BZT concentration increased. Maximum strain values of 0.33% were observed at 5-40-55 accompanied by a large d(33)* = 547 pm/V. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4714346]