It was noted that a pronounced splitting of the strongest Bragg reflections was sometimes observed during high-resolution X-ray diffraction studies of this decagonal phase. This had previously been interpreted as constituting evidence for a twinned micro-crystalline state with large lattice parameters. It was shown here that the metrics could be perfectly reproduced by modelling a twinned 1-dimensional quasicrystal rather than a twinned 3-dimensional crystalline phase. The split peak positions could be easily reproduced by applying a linear phason strain to the ideal decagonal quasicrystal, with subsequent 5-fold twinning. An anisotropic broadening of all of the investigated reflections led to the suggestion that a non-linear phason-strain component existed.

M.Kalning, S.Kek, H.G.Krane, V.Dorna, W.Press, W.Steurer: Physical Review B, 1997, 55[1], 187-92