The X-ray diffracted intensity changes considerably when a static electric field is
applied perpendicularly to a X- or Y-cut LiNbO3 platelet-shaped crystal. Section
diffraction images (topographs) recorded using synchrotron radiation in transmission
mode reveal the curvature of the lattice planes under such a field. A theoretical
analysis based on the equations of electro-mechanical field in a piezoelectric
medium together with chemical etching experiments allows us to explain this effect.
Tiny inverted ferroelectric doMayns produced by the applied field exert a strain on
the non-inverted bulk leading to the observed curvature of the lattice planes. This
approach seems to be valid for other piezoelectric crystals of various symmetry
classes.