Materials Data on Na4Ca4Be4AlSi7(O6F)4 by Materials Project

Abstract

Na4Ca4Be4AlSi7(O6F)4 crystallizes in the tetragonal I-4 space group. The structure is three-dimensional. Na is bonded in a 8-coordinate geometry to six O and two equivalent F atoms. There are a spread of Na–O bond distances ranging from 2.34–2.88 Å. There are one shorter (2.40 Å) and one longer (2.68 Å) Na–F bond lengths. Ca is bonded in a 8-coordinate geometry to seven O and one F atom. There are a spread of Ca–O bond distances ranging from 2.39–2.74 Å. The Ca–F bond length is 2.55 Å. Be is bonded to three O and one F atom to form BeO3F tetrahedra that share corners with three SiO4 tetrahedra. There is one shorter (1.60 Å) and two longer (1.66 Å) Be–O bond length. The Be–F bond length is 1.59 Å. Al is bonded to four equivalent O atoms to form AlO4 tetrahedra that share corners with four equivalent SiO4 tetrahedra. All Al–O bond lengths are 1.77 Å. There are three inequivalent Si sites. In the first Si site, Si is bonded to four equivalent O atoms to form SiO4 tetrahedra that share corners with four equivalent BeO3F tetrahedra. All Si–O bond lengths are 1.65 Å. In the second Si site, Si is bonded to four O atoms to form SiO4 tetrahedra that share corners with two equivalent BeO3F tetrahedra and corners with two equivalent SiO4 tetrahedra. There is two shorter (1.64 Å) and two 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 a cornercorner with one BeO3F tetrahedra, a cornercorner with one AlO4 tetrahedra, and a cornercorner with one SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.68 Å. There are six inequivalent O sites. In the first O site, O is bonded in a 4-coordinate geometry to one Na, one Ca, one Be, and one Si atom. In the second O site, O is bonded in a 4-coordinate geometry to one Na, two equivalent Ca, and one Si atom. In the third O site, O is bonded in a 2-coordinate geometry to one Na, one Ca, one Al, and one Si atom. In the fourth O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent Na and two Si atoms. In the fifth O site, O is bonded in a 2-coordinate geometry to two equivalent Ca, one Be, and one Si atom. In the sixth O site, O is bonded in a 2-coordinate geometry to one Na, one Ca, one Be, and one Si atom. F is bonded in a 1-coordinate geometry to two equivalent Na, one Ca, and one Be atom.