DOI: 10.17188/1711286
title: Materials Data on KMg3AlSi3O11F by Materials Project

description: KMg3AlSi3O11F crystallizes in the monoclinic Cc space group. The structure is two-dimensional and consists of two KMg3AlSi3O11F sheets oriented in the (0, 0, 1) direction. K is bonded in a 6-coordinate geometry to six O atoms. There are a spread of K–O bond distances ranging from 2.99–3.06 Å. There are three inequivalent Mg sites. In the first Mg site, Mg is bonded to five O and one F atom to form MgO5F octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, and edges with six MgO5F octahedra. There are a spread of Mg–O bond distances ranging from 2.05–2.16 Å. The Mg–F bond length is 2.07 Å. In the second Mg site, Mg is bonded to five O and one F atom to form MgO5F octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, and edges with six MgO5F octahedra. There are a spread of Mg–O bond distances ranging from 2.02–2.16 Å. The Mg–F bond length is 2.00 Å. In the third Mg site, Mg is bonded to five O and one F atom to form MgO5F octahedra that share a cornercorner with one AlO4 tetrahedra, corners with three SiO4 tetrahedra, and edges with six MgO5F octahedra. There are a spread of Mg–O bond distances ranging from 2.05–2.12 Å. The Mg–F bond length is 2.09 Å. Al is bonded to four O atoms to form AlO4 tetrahedra that share corners with three MgO5F octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 61–62°. There are a spread of Al–O bond distances ranging from 1.73–1.78 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO5F octahedra and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–58°. There is three shorter (1.62 Å) and one longer (1.67 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 MgO5F octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–58°. There is one shorter (1.63 Å) and three longer (1.66 Å) Si–O bond length. In the third Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with three MgO5F octahedra and corners with three equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–59°. There is one shorter (1.63 Å) and three longer (1.66 Å) Si–O bond length. There are eleven inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the second O site, O is bonded in a 2-coordinate geometry to two equivalent K, one Al, and one Si atom. In the third O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the fourth O site, O is bonded in a distorted bent 150 degrees geometry to two equivalent K, one Al, and one Si atom. In the fifth O site, O is bonded in a distorted rectangular see-saw-like geometry to three Mg and one Si atom. In the sixth O site, O is bonded in a rectangular see-saw-like geometry to three Mg and one Si atom. In the seventh O site, O is bonded in a rectangular see-saw-like geometry to three Mg and one Si atom. In the eighth O site, O is bonded in a 2-coordinate geometry to two equivalent K, one Al, and one Si atom. In the ninth O site, O is bonded in a bent 150 degrees geometry to two Si atoms. In the tenth O site, O is bonded in a distorted tetrahedral geometry to three Mg and one Al atom. In the eleventh O site, O is bonded in a trigonal non-coplanar geometry to three Mg atoms. F is bonded in a distorted trigonal non-coplanar geometry to three Mg atoms.