  Quantitative strain measurements of the 1:1 B-site cation ordered domains,
antiphase boundaries and dislocations in a highly ordered Pb(Sc1/2Ta1/2)O3
ceramic have been carried out by high-resolution transmission electron
microscopy and geometric phase analysis. A phase shift of PI between two
adjacent ordered domains across an antiphase boundary are determined
unambiguously. The maximum in-plane strain and lattice rotation induced by a
dislocation are 9.5% and 5.4deg, respectively. In a defect-free antiphase
boundary, the maximum in-plane strain and lattice rotation are 1.8% and 0.9deg,
respectively. The strain mainly concentrates inside the antiphase boundary.
