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Figure 3
Sketch of the crystal structure of Sr2Pt8−xAs. (a) and (b) are portions of the Sr2Pt7.285As IM structure with the modulation wavevector q = 0.6038c*. (b) and (c) represent the commensurate superstructure approximation with q = 0.6c*. Different colours show five different atomic sites of Pt, Pt1, Pt2 and Pt3 (grey) forming a layer of edge-sharing AsPt6 bipyramids (green) centred by As (blue background). This layer of AsPt6 bipyramids is identical in both the IM structure and its commensurate approximation. Pt4 (brown) and Pt5 (blue) form the `metallic' corrugated grids (red background), which are aperiodic along the c axis in the IM structure. The short Pt–Pt contacts of 2.4–2.74 Å are shown by lines.

IUCrJ
Volume 5| Part 4| July 2018| Pages 470-477
ISSN: 2052-2525
https://doi.org/10.1107/S2052252518007303