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

Abstract

Single crystals have been grown in the (Bi1/2Na1/2)1−xBaxZryTi1−yO3 perovskite system by a self-flux method over the range of compositions y=0.04 and x=0.06–0.012. Rhombohedral (x⩽0.08) and tetragonal phase (x⩾0.09) 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 Q11=(2.8–3.3)×10−2 m4/C2. Due to induced polarizations that do not saturate at fields beyond 50 kV/cm, high electrostrictive strains are obtained. Rhombohedral phase crystals exhibit d33 up to 1180 pC/N and strains of S3=0.3% before electrical breakdown, while tetragonal phase crystals exhibit d33 up to 2000 pC/N and S3 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.