DOI: 10.17188/1705834
title: Materials Data on Ca4Mn6Si5O28 by Materials Project

description: Ca4Mn6Si5O28 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent SiO4 tetrahedra, edges with six MnO6 octahedra, an edgeedge with one CaO7 pentagonal bipyramid, and an edgeedge with one SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.26–2.46 Å. In the second Ca2+ site, Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with five SiO4 tetrahedra, edges with two equivalent MnO6 octahedra, an edgeedge with one CaO7 pentagonal bipyramid, and an edgeedge with one SiO4 tetrahedra. There are a spread of Ca–O bond distances ranging from 2.37–2.58 Å. There are two inequivalent Mn+4.67+ sites. In the first Mn+4.67+ site, Mn+4.67+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four SiO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with two CaO7 pentagonal bipyramids. There are a spread of Mn–O bond distances ranging from 1.90–2.13 Å. In the second Mn+4.67+ site, Mn+4.67+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent MnO6 octahedra, corners with two equivalent SiO4 tetrahedra, edges with two equivalent MnO6 octahedra, and edges with four equivalent CaO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 14°. There are a spread of Mn–O bond distances ranging from 1.90–2.36 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six MnO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, and an edgeedge with one CaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 48–58°. There are a spread of Si–O bond distances ranging from 1.61–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four equivalent MnO6 octahedra, corners with two equivalent CaO7 pentagonal bipyramids, a cornercorner with one SiO4 tetrahedra, and an edgeedge with one CaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 48–59°. There is two shorter (1.63 Å) and two longer (1.67 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with six equivalent CaO7 pentagonal bipyramids and corners with two equivalent SiO4 tetrahedra. There is two shorter (1.63 Å) and two longer (1.71 Å) Si–O bond length. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a water-like geometry to two equivalent Mn+4.67+ atoms. In the second O2- site, O2- is bonded in a water-like geometry to two equivalent Mn+4.67+ atoms. In the third O2- site, O2- is bonded to one Ca2+, two equivalent Mn+4.67+, and one Si4+ atom to form distorted edge-sharing OCaMn2Si trigonal pyramids. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to one Ca2+, two equivalent Mn+4.67+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted see-saw-like geometry to two equivalent Ca2+ and two equivalent Mn+4.67+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ca2+ and one Si4+ atom. In the seventh O2- site, O2- is bonded to one Ca2+, two equivalent Mn+4.67+, and one Si4+ atom to form distorted edge-sharing OCaMn2Si trigonal pyramids. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ca2+ and two equivalent Mn+4.67+ atoms. In the tenth O2- site, O2- is bonded in a single-bond geometry to one Ca2+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mn+4.67+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mn+4.67+, and one Si4+ atom.