Materials Data on KMg3(SiO3)4 by Materials Project

Abstract

KMg3(SiO3)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K is bonded to twelve O atoms to form KO12 cuboctahedra that share edges with six equivalent KO12 cuboctahedra and edges with twelve SiO4 tetrahedra. There are a spread of K–O bond distances ranging from 3.15–3.22 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.98–2.14 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with four SiO4 tetrahedra and edges with six equivalent MgO6 octahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.12 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra, corners with three equivalent SiO4 tetrahedra, and edges with three equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 54–59°. There is one shorter (1.61 Å) and three longer (1.66 Å) Si–O bond length. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO6 octahedra, corners with three equivalent SiO4 tetrahedra, and edges with three equivalent KO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is one shorter (1.61 Å) and three longer (1.66 Å) Si–O bond length. There are six inequivalent O sites. In the first O site, O is bonded in a rectangular see-saw-like geometry to three Mg and one Si atom. In the second O site, O is bonded in a distorted bent 150 degrees geometry to two equivalent K and two Si atoms. In the third O site, O is bonded in a rectangular see-saw-like geometry to three Mg and one Si atom. In the fourth O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent K and two Si atoms. In the fifth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Mg atoms. In the sixth O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent K and two Si atoms.