Materials Data on Ca2Mg(CO3)3 by Materials Project

Abstract

Ca2Mg(CO3)3 is Calcite-derived structured and crystallizes in the trigonal P31c space group. The structure is three-dimensional. there are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with three equivalent CaO6 octahedra and corners with three equivalent MgO6 octahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are three shorter (2.38 Å) and three longer (2.44 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with three equivalent MgO6 octahedra and corners with three equivalent CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 62°. There are three shorter (2.37 Å) and three longer (2.42 Å) Ca–O bond lengths. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with three equivalent CaO6 octahedra and corners with three equivalent CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 62°. There are three shorter (2.11 Å) and three longer (2.12 Å) Mg–O bond lengths. There are three inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All C–O bond lengths are 1.30 Å. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All C–O bond lengths are 1.30 Å. In the third C4+ site, C4+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All C–O bond lengths are 1.30 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ca2+ and one C4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mg2+, and one C4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Mg2+, and one C4+ atom.