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Dissociation of basal dislocations in hexagonal barium titanate
Author(s) -
WU Y. C.,
HO N. J.,
LU H. Y.
Publication year - 2005
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.2005.01530.x
Subject(s) - crystallography , dislocation , peierls stress , stacking fault , materials science , substructure , transmission electron microscopy , slip (aerodynamics) , partial dislocations , condensed matter physics , glide plane , chemistry , physics , dislocation creep , nanotechnology , structural engineering , engineering , thermodynamics
Summary Dislocation substructure in hot‐pressed hexagonal BaTiO 3 ceramics was analysed by transmission electron microscopy. Two dislocation networks each consisting of dissociated half‐partials were determined for the Burgers vectors ( b ) using the g · b = 0 effective invisibility criteria, and the true directions ( u ) by trace analysis. Each of the networks contains three partial nodes that are in the form: 1/3[010]+1/3[100]+1/3[100]+1/3[100] = 0, where four partials meet at a point and the Burgers vectors are conserved, as analysed by the weak‐beam dark field technique. Basal dislocation with b b = 1/3<110> is dissociated into two prism plane half‐partials with b hp = 1/3<100> by: 1/3<110> → 1/3<010> + 1/3<100>. Dissociation of basal dislocation by a glide mechanism creates a stacking fault when shear occurs along <100> in the c‐layer of (000 l ), where l = 1, 3, 4 and 6, of the (chc) 1 (chc) 2 (or (CBC)(ABA)) stacking sequence. The slip system of 1/3<110>(0001) in hexagonal BaTiO 3 has been activated at 1300 °C by hot‐pressing under ∼25.8 MPa. Plastic flow contributing to the densification of hexagonal BaTiO 3 ceramics occurs through glide of half‐partials in the basal plane by a glide‐controlled dislocation glide mechanism. Dislocation motion governed by the Peierls mechanism, where velocity is determined by both correlated and uncorrelated double‐kink nucleation on two half‐partials, is discussed.