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Figure 3
Multi-temperature structural data for Cu2−xSe. (a) Normalized cell parameters for Cu1.95Se. At 100 K the hexagonal cell parameters are a = 4.092 (1) Å, c = 20.459 (9) Å and V = 296.7 (2) Å3. (b) Changes in inter-layer distances as a function of temperature, red is the long distance and black short. The two last data points in both figures are from the cubic α-phase. All uncertainties are smaller than the size of the symbols. (c) Three stages of the copper movement from the thick copper rich layer (red) to the thinner copper deficient layer (black). Copper atoms are represented as spheres, with trapeze symbols indicating Cu sites disordered about a threefold rotation axis, while triangles indicate disordered copper tetrahedra in the α-phase.

IUCrJ
Volume 4| Part 4| July 2017| Pages 476-485
ISSN: 2052-2525
https://doi.org/10.1107/S2052252517005553