Migration of Half Partial Dislocations in the Planar Fault Plane of Hexagonal Barium Titanate
Abstract:The prism plane half partials with Burgers vector bPr= 1/3 ×〈01 10〉 dissociated from the perfect basal dislocations with bB= 1/3〈 12 10〉 embedded in an α-type extended planar stacking fault of hexagonal (h-)BaTiO3 have been analyzed by transmission electron microscopy. It is found that the dissociation of a series of basal dislocations occurred by glide in the fault plane (0002). However, migrating of the pair partials trailing behind in the fault plane was impeded by the leading pair. Under the applied stress in hot pressing, these partials were gradually piled up with successively decreasing separation between each pair. That has consequently led to partial separations ranging between ∼195 and 56 nm. One partial dislocation (p1) belonging initially to the leading pair partials has moved to another plane by a mixed mechanism of glide in (0002) and climb down in (0 110) by 1/2[000 1] (i.e., (1/2)c). The climbing partial has become an obstacle hindering dislocation migration in the fault plane. Determining the secondary pyramidal plane (0 112) connecting the leading half partial allows us to propose that the p1 partial migrating by glide and climb has arrived at another planar fault plane (0005) during hot pressing. The stages of how half partials were created, separated in fault plane, and arrived gradually at the present configuration are proposed and schematically illustrated. The significance of climb-controlled dislocation glide mechanism in the hot pressing of h-BaTiO3 is discussed.
Document Type: Research Article
Affiliations: 1: Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan 2: Centre for Nanoscience, Institute of Materials Science and Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
Publication date: 2007-01-01