Relaxor single crystals in the (Bi1/2Na1/2)(1-x)BaxZryTi1-yO3 system exhibiting high electrostrictive strain

Single crystals have been grown in the (Bi1/2Na1/2)(1-x)BaxZryTi1-yO3 perov skite system by a self-flux method over the range of compositions y=0.04 an d x=0.06-0.012. Rhombohedral (x less than or equal to0.08) and tetragonal p hase (x greater than or equal to0.09) crystals have been obtained that do n ot show polarization or field-induced strain hysteresis characteristics of a ferroelectric. However, a frequency-dispersive dielectric response charac teristic of a relaxor ferroelectric, and predominantly electrostrictive act uation, 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 a t fields beyond 50 kV/cm, high electrostrictive strains are obtained. Rhomb ohedral 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 highe st electrostrictive strains yet reported for an inorganic compound. The unu sually high electrostriction is discussed in relation to an energy landscap e that allows ferroelastic and ferroelectric distortions to be simultaneous ly accessible at the nanometer scale. (C) 2001 American Institute of Physic s.