A 6-dimensional description of 2 approximants of a decagonal phase was presented. Both structures were shown to be completely described by 2 sorts of overlapping cluster: Bergman and pseudo-Mackay. On the basis of the structural defects which were observed by using high-resolution electron microscopy, a possible structural transformation between the 2 phases was considered. The transformation mechanism involved the motion of linear defects which were lines of phasons rather than dislocations. The atomic jumps which were related to defect motion occurred over distances of less than 0.3nm and were shown to be phason jumps since they resulted from translations of the windows (atomic surfaces) in perpendicular space. Experimental observations suggested that the motion of phason defects could also be driven by a chemical composition gradient.

Phason Defects in Al-Pd-Mn Approximant Phases L.Beraha, M.Duneau, H.Klein, M.Audier: Philosophical Magazine A, 1998, 78[2], 345-72