Transmission electron microscopic observations of as-cast samples of an icosahedral quasicrystal revealed the presence of planar and line defects. By using dark-field and weak-beam imaging techniques, the planar defects were tentatively identified as being -type boundaries and low-angle sub-grain boundaries, while the line defects were found to be isolated dislocations. The characteristics of the defects were determined by performing extensive tilting experiments and conventional extinction contrast analysis. The isolated dislocations were found to have a Burgers vector that was directed along a 5-fold symmetry axis in physical space and which was of screw type.

N.Baluc, D.P.Yu, M.Kleman: Philosophical Magazine Letters, 1995, 72[1], 1-9