Materials Data on CaMn7O12 by Materials Project

Abstract

CaMn7O12 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share faces with eight MnO6 octahedra. There are six shorter (2.63 Å) and six longer (2.72 Å) Ca–O bond lengths. There are three inequivalent Mn+3.14+ sites. In the first Mn+3.14+ site, Mn+3.14+ is bonded in a square co-planar geometry to four O2- atoms. All Mn–O bond lengths are 1.96 Å. In the second Mn+3.14+ site, Mn+3.14+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six MnO6 octahedra and faces with two equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 40–42°. There are a spread of Mn–O bond distances ranging from 1.95–2.05 Å. In the third Mn+3.14+ site, Mn+3.14+ is bonded to six equivalent O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO6 octahedra and faces with two equivalent CaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 42°. All Mn–O bond lengths are 1.97 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and three Mn+3.14+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+ and three Mn+3.14+ atoms.