Mechanical stresses and giant piezoresponse of the surface of textured K$_{2}$Sr$_{4}$Nb$_{10}$O$_{30}$ ceramics

Crystallographic characteristics of K$_{2}$Sr$_{4}$Nb$_{10}$O$_{30}$ ceramics have been compared to experimental data on the surface piezoresponse studied by method of scanning probe microscopy, which was used to estimate relative values of $d_{33}$ piezomodulus. Depending on the orientation of a ceramic sample surface relative to the axis of texture, these values turned out to be 62 or 58 times greater than the moduli of isotropic samples. The observed giant piezoresponse of the ceramic surface can be explained by anisotropic deformation of the crystalline lattice under pressure during hot pressing. The role of domain boundaries and polar nanoregions is discussed.