Ultrahigh electrostrain in Pb-free piezoceramics: Effect of bending

Recently several reports showing ultra-high electrostrain (> 1 appeared in Pb-free piezoceramics. However, there is lack of clarity on the nature of the ultrahigh strain. Here, we demonsrate that the ultrahigh strain is a consequence of bending of the disc. We show that the propensity for bending arises from the difference in the response magnitude of the grains at the positive and negative surfaces of the piezoceramic when the field is applied.