Materials Data on BaMg2Si2O7 by Materials Project

Abstract

BaMg2Si2O7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.75–3.25 Å. There are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with four SiO4 tetrahedra and corners with two equivalent MgO5 trigonal bipyramids. There is two shorter (1.97 Å) and two longer (1.99 Å) Mg–O bond length. In the second Mg2+ site, Mg2+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Mg–O bond distances ranging from 2.02–2.65 Å. In the third Mg2+ site, Mg2+ is bonded to five O2- atoms to form distorted MgO5 trigonal bipyramids that share a cornercorner with one MgO4 tetrahedra, corners with three SiO4 tetrahedra, an edgeedge with one SiO4 tetrahedra, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Mg–O bond distances ranging from 1.97–2.25 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, and corners with two equivalent MgO5 trigonal bipyramids. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO4 tetrahedra, a cornercorner with one SiO4 tetrahedra, a cornercorner with one MgO5 trigonal bipyramid, and an edgeedge with one MgO5 trigonal bipyramid. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Mg2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Mg2+ and one Si4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Mg2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, two Mg2+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two equivalent Mg2+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Ba2+, two Mg2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+ and two Si4+ atoms.