Nanoindentation of BaTiO₃: dislocation nucleation and mechanical twinning

Abstract

This paper presents a study of the deformation mechanisms of barium titanate under nanoindentation. The (0 0 1) and (1 1 0) crystallographic orientations of BaTiO3 giant grains were indented and critical mean contact pressures for dislocation nucleation were extracted from the indentation curves. The orientation of the dislocation slip lines was identified by atomic force microscopy, showing that the ⟨1 1 0⟩{1 1 0} glide systems were activated. Twin bands, observed on both orientations, also occur on the {1 1 0} habit planes and actively participate in the accommodation of the plastic deformation. Furthermore, dislocation pile-ups introduced by spherical indentations have shown a close relation between dislocations and twinning formation.