  Recently we found that when conventional bulk polycrystalline piezoceramics
discs (~ 10 mm diameter) are thinned down to thickness ~ 200 microns or below,
the measured unipolar electrostrain (UES) values increased phenomenally
(arXiv:2208.07134). Here we demonstrate that this anomalous phenomenon
correlates strongly with the decrease in the degree of mutual mechanical
clamping between the grains which in turn enables enhanced switching of the
ferroelastic domains.
