Relaxor single crystals in the (Bi1/2Na1/2)1-xBaxZryTi1-yO3 system exhibiting high electrostrictive strain

Single crystals have been grown in the (Bi1/2Na1/2)(1-x)BaxZryTi1-yO3 perovskite system by a self-flux method over the range of compositions y=0.04 and x=0.06-0.012. Rhombohedral (x less than or equal to0.08) and tetragonal phase (x greater than or equal to0.09) crystals have been obtained that do not show polarization or field-induced strain hysteresis characteristics of a ferroelectric. However, a frequency-dispersive dielectric response characteristic of a relaxor ferroelectric, and predominantly electrostrictive actuation, is observed across the range of compositions tested, with Q(11)=(2.8-3.3)x10(-2) m(4)/C-2. Due to induced polarizations that do not saturate at fields beyond 50 kV/cm, high electrostrictive strains are obtained. Rhombohedral phase crystals exhibit d(33) up to 1180 pC/N and strains of S-3=0.3% before electrical breakdown, while tetragonal phase crystals exhibit d(33) up to 2000 pC/N and S-3 up to 0.45% strain. These crystals show the highest electrostrictive strains yet reported for an inorganic compound. The unusually high electrostriction is discussed in relation to an energy landscape that allows ferroelastic and ferroelectric distortions to be simultaneously accessible at the nanometer scale. (C) 2001 American Institute of Physics.