Phason strain

The offset ds introduced by a phason plane can be interpreted as the vertical component of the phason-plane strain field. Since the phason plane turns hexagon columns into their alternate orientation, its strain field has in addition a lateral component corresponding to a translation of half a lattice constant along the [10 0] direction. The total phason-plane strain field can then be described by the displacement vector 7 =1/2(1 0 - 1/r ), which was experimentally verified by means of fringe-contrast analysis in TEM [37]. 

The overall appearance of the metadislocation resembles a dislocation in a simple metal but the differences are obvious the apparent extension of the strain field of the metadislocation is larger by more than one order of magnitude, and the associated phasons are not inserted hal lanes like those of an edge dislocation in a simple metal, but consist of a locally transformed area. Historically, the first observed metadislocations in E2s-Al-Pd-Mn were interpreted as defects in a structure of defects (Section 3.2) and were, therefore, termed metadislocations [1]. 

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