Strain actuation of barium titanate single crystals under electromechanical loading in the non-polar [110] direction

Abstract

The switching characteristics of BaTiO3 single crystals subjected to uniaxial electromechanical loading in the non-polar [110] direction at room temperature and 55 ° C were investigated. Polarization and strain hysteresis measurements in the [110] direction revealed that under the combination of large in-plane switching coercivities and a strong out-of-plane depolarization field (induced by the shape irregularity and large unshielded surfaces of the crystal sample), strain-inducing 90° in-plane to out-of-plane (or vice versa) switching was the dominant switching behavior even in the absence of mechanical bias. By lowering the in-plane switching coercivities, which was achieved by increasing the loading temperature from room temperature to 55 ° C, a contrasting non-strain-inducing switching behavior characterized by 90° and/or 180° switches between the in-plane variants was observed instead. The contrasting switching behavior at two different temperatures indicates that apart from the bias stress magnitude, the combined effect of the depolarization field and switching coercivity is another critical factor governing the strain actuation of BaTiO3 single crystals. The [110] electromechanical loading responses reveal the possibility of increasing the strain capacity of BaTiO3 single crystals by introducing accompanying depolarization fields which promote strain-inducing 90° switching. Such an approach could be potentially useful when bias stress-activated ferroelastic switching is not attainable.