DOI: 10.17188/1731505
title: Materials Data on KNaCaMg5Si8(O11F)2 by Materials Project

description: KNaCaMg5Si8O22F2 is Esseneite-derived structured and crystallizes in the triclinic P1 space group. The structure is three-dimensional. K1+ is bonded in a 2-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.61–3.32 Å. Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.91 Å. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.86 Å. There are five inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four O2- and two F1- atoms to form MgO4F2 octahedra that share corners with four SiO4 tetrahedra and edges with five MgO4F2 octahedra. There are two shorter (2.03 Å) and two longer (2.08 Å) Mg–O bond lengths. There are one shorter (2.11 Å) and one longer (2.12 Å) Mg–F bond lengths. In the second Mg2+ site, Mg2+ is bonded to four O2- and two F1- atoms to form MgO4F2 octahedra that share corners with four SiO4 tetrahedra and edges with five MgO4F2 octahedra. All Mg–O bond lengths are 2.08 Å. There are one shorter (2.07 Å) and one longer (2.08 Å) Mg–F bond lengths. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SiO4 tetrahedra and edges with three MgO4F2 octahedra. There are a spread of Mg–O bond distances ranging from 2.00–2.24 Å. In the fourth Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six SiO4 tetrahedra and edges with three MgO4F2 octahedra. There are a spread of Mg–O bond distances ranging from 2.04–2.17 Å. In the fifth Mg2+ site, Mg2+ is bonded to four O2- and two F1- atoms to form MgO4F2 octahedra that share corners with four SiO4 tetrahedra and edges with six MgO4F2 octahedra. There are a spread of Mg–O bond distances ranging from 2.07–2.09 Å. Both Mg–F bond lengths are 2.03 Å. There are eight inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–57°. There are a spread of Si–O bond distances ranging from 1.61–1.71 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 33–56°. There are a spread of Si–O bond distances ranging from 1.61–1.71 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–57°. There are a spread of Si–O bond distances ranging from 1.59–1.68 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 35–57°. There are a spread of Si–O bond distances ranging from 1.59–1.69 Å. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–61°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–61°. There are a spread of Si–O bond distances ranging from 1.61–1.66 Å. In the seventh Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–60°. There are a spread of Si–O bond distances ranging from 1.62–1.65 Å. In the eighth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three MgO4F2 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–60°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are twenty-two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+, two Mg2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+, two Mg2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+, two Mg2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ca2+, two Mg2+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ca2+, and two Si4+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ca2+, and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Na1+, and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Na1+, and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to three Mg2+ and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ca2+, and two Si4+ atoms. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to one K1+, one Ca2+, and two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Na1+, and two Si4+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+, one Na1+, and two Si4+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Mg2+, and one Si4+ atom. In the eighteenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ca2+, one Mg2+, and one Si4+ atom. In the nineteenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Mg2+, and one Si4+ atom. In the twentieth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Mg2+, and one Si4+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Si4+ atoms. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to one K1+ and two Si4+ atoms. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted trigonal non-coplanar geometry to three Mg2+ atoms. In the second F1- site, F1- is bonded in a distorted trigonal non-coplanar geometry to three Mg2+ atoms.