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Figure 3
(a) Thermal expansion tensor in MgSO4·H2O at 113 K (Tref = 293 K), with green indicating positive values, red indicating negative values; (b) cross sections of the thermal expansion tensors of kieserite-type compounds M2+SO4·H2O (M2+ = Mg, Fe, Co, Ni) at 113 K (Tref = 293 K) in the ac plane, superimposed on a respective projection of the structure of kieserite at 113 K. For increasing temperature, black arrows show the sense of tetrahedral rotations around the twofold axis, red arrows indicate the resulting opposing translations of neighboring octahedral–tetrahedral chains within the ac plane (see text). The tensor surface and cross sections were prepared with the program WinTensor (Kaminski, 2014BB41).

IUCrJ
Volume 9| Part 2| March 2022| Pages 194-203
ISSN: 2052-2525
https://doi.org/10.1107/S2052252521012720