Materials Data on NaMn7O12 by Materials Project
NaMn7O12 crystallizes in the cubic Im-3 space group. The structure is three-dimensional. Na1+ is bonded to twelve equivalent O2- atoms to form NaO12 cuboctahedra that share faces with eight equivalent MnO6 octahedra. All Na–O bond lengths are 2.70 Å. There are two inequivalent Mn+3.29+ sites. In the first Mn+3.29+ site, Mn+3.29+ is bonded to six equivalent O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO6 octahedra and faces with two equivalent NaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 40°. All Mn–O bond lengths are 1.98 Å. In the second Mn+3.29+ site, Mn+3.29+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Mn–O bond lengths are 1.95 Å. O2- is bonded in a 3-coordinate geometry to one Na1+ and three Mn+3.29+ atoms.