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Figure 11
(a) Sequences of FeO5 polyhedra in (Fe2O2+δ) rock-salt blocks of Sr4Fe6O12+δ phases with different α components of the modulation vector. Oxygen atoms in the tetrahedral interstices are denoted as Ot. Trigonal bipyramids and tetragonal pyramids FeO5 are denoted TB and TP, respectively. (b) Crystal structure of Sr4Fe6O12.8. FeO6 octahedra are yellow, FeO5 polyhedra are blue and Sr atoms are shown as brown spheres.

IUCrJ
Volume 2| Part 1| January 2015| Pages 137-154
ISSN: 2052-2525
doi:10.1107/S2052252514023550