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Figure 1
Crystal structures of (a) the aristotype (tetragonal, I4/mmm) and (b) the ambient-temperature (monoclinic, B1a1) phases.

IUCrJ
Volume 6| Part 3| May 2019| Pages 438-446
ISSN: 2052-2525
https://doi.org/10.1107/S2052252519003804