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Figure 2
Stereographic projection of the major pseudocubic directions in perovskites, viewed down [001]. Directions closest to [001] are marked as dots. The green solid circles refer to the 〈111〉 directions (three-fold symmetry axes for rhombohedral cation displacements), black solid circles mark the 〈110〉 directions (two-fold axis of orthorhombic symmetry) and black open circles refer to the [001] directions (four-fold axis for tetragonal symmetry). Blue solid and open circles represent possible MA and MB directions, respectively, on the {110} monoclinic mirror planes. Red solid circles represent possible MC directions on the {100} monoclinic mirror planes.

IUCrJ
Volume 5| Part 1| January 2018| Pages 73-81
ISSN: 2052-2525
https://doi.org/10.1107/S2052252517016633