Materials Data on BaMn2FeSi2O9 by Materials Project

BaMn2FeSi2O9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.76–3.02 Å. There are three inequivalent Mn+2.50+ sites. In the first Mn+2.50+ site, Mn+2.50+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with two equivalent SiO4 tetrahedra, corners with two equivalent FeO5 trigonal bipyramids, and edges with six MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.13–2.26 Å. In the second Mn+2.50+ site, Mn+2.50+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four equivalent SiO4 tetrahedra and edges with six MnO6 octahedra. There are two shorter (1.92 Å) and four longer (2.20 Å) Mn–O bond lengths. In the third Mn+2.50+ site, Mn+2.50+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with four equivalent SiO4 tetrahedra, corners with two equivalent FeO5 trigonal bipyramids, and edges with six MnO6 octahedra. There are two shorter (2.14 Å) and four longer (2.29 Å) Mn–O bond lengths. Fe3+ is bonded to five O2- atoms to form distorted FeO5 trigonal bipyramids that share corners with three MnO6 octahedra and corners with four equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 62–64°. There is one shorter (1.89 Å) and four longer (2.00 Å) Fe–O bond length. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MnO6 octahedra, a cornercorner with one SiO4 tetrahedra, and corners with two equivalent FeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 56–62°. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Fe3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, one Fe3+, and one Si4+ atom. In the third O2- site, O2- is bonded to three Mn+2.50+ and one Fe3+ atom to form a mixture of distorted edge and corner-sharing OMn3Fe tetrahedra. In the fourth O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Mn+2.50+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ba2+ and two equivalent Si4+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Mn+2.50+ and one Si4+ atom.