Collinear partial dislocations in barium titanate perovskite

Dislocation substructures in CO2-laser-sintered undoped BaTiO3 have been investigated via transmission electron microscopy. Deformation of BaTiO3 at 1390 °C occurs when the slip system of 〈100〉{001} is activated by the intrinsic thermodynamic driving force for sintering. Dissociation of dislocations with Burgers vector b1=[001] into two collinear partials of b2=1/2[001] and b3=1/2[001] has been identified unambiguously using weak-beam dark-field imaging. Part of the b3 partial further changes to a scallop-shape half-loop of b3′=1/2[100] by a non-conservative loop formation mechanism of mixed climb and glide in the {111} plane. Results suggest that plastic flow by dislocation mechanisms contribute to the densification of BaTiO3 at 1390 °C. It takes place by a climb-controlled glide mechanism, which is rate-determined kinetically by the lattice diffusion of Ba2+.