Materials Data on CaMg(SiO3)2 by Materials Project

CaMgSi2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent SiO4 tetrahedra and edges with two equivalent CaO6 octahedra. There are a spread of Ca–O bond distances ranging from 2.29–2.48 Å. Mg2+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There is two shorter (1.95 Å) and two longer (2.02 Å) Mg–O bond length. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent CaO6 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–66°. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Mg2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca2+, one Mg2+, and one Si4+ atom.