Materials Data on Ca7MgMn8O24 by Materials Project

Abstract

Ca7MgMn8O24 is (Cubic) Perovskite-derived structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with twelve CaO12 cuboctahedra, faces with two equivalent MgO12 cuboctahedra, faces with four equivalent CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. All Ca–O bond lengths are 2.68 Å. In the second Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent MgO12 cuboctahedra, corners with eight equivalent CaO12 cuboctahedra, faces with six CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. There are eight shorter (2.68 Å) and four longer (2.71 Å) Ca–O bond lengths. In the third Ca2+ site, Ca2+ is bonded to twelve equivalent O2- atoms to form CaO12 cuboctahedra that share corners with twelve equivalent CaO12 cuboctahedra, faces with six equivalent CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. All Ca–O bond lengths are 2.68 Å. Mg2+ is bonded to twelve equivalent O2- atoms to form MgO12 cuboctahedra that share corners with twelve equivalent CaO12 cuboctahedra, faces with six equivalent CaO12 cuboctahedra, and faces with eight equivalent MnO6 octahedra. All Mg–O bond lengths are 2.65 Å. Mn4+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with six equivalent MnO6 octahedra, a faceface with one MgO12 cuboctahedra, and faces with seven CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. There is three shorter (1.89 Å) and three longer (1.90 Å) Mn–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to three Ca2+, one Mg2+, and two equivalent Mn4+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to four Ca2+ and two equivalent Mn4+ atoms.