Materials Data on Ca2MgSi2O7 by Materials Project
Ca2MgSi2O7 is Esseneite-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.40–2.92 Å. In the second Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.64 Å. Mg2+ is bonded to four O2- atoms to form distorted MgO4 tetrahedra that share corners with four SiO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 1.93–1.99 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 SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+, one Mg2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mg2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted tetrahedral geometry to two Ca2+, one Mg2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+, one Mg2+, and one Si4+ atom.