Materials Data on NaCaBeSi2O6F by Materials Project

Abstract

NaCaBeSi2O6F crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. Na1+ is bonded in a 8-coordinate geometry to six O2- and two equivalent F1- atoms. There are a spread of Na–O bond distances ranging from 2.37–2.96 Å. There are one shorter (2.42 Å) and one longer (2.80 Å) Na–F bond lengths. Ca2+ is bonded in a 7-coordinate geometry to six O2- and one F1- atom. There are a spread of Ca–O bond distances ranging from 2.37–2.67 Å. The Ca–F bond length is 2.53 Å. Be2+ is bonded to three O2- and one F1- atom to form BeO3F tetrahedra that share corners with three SiO4 tetrahedra. There are a spread of Be–O bond distances ranging from 1.61–1.66 Å. The Be–F bond length is 1.60 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one BeO3F tetrahedra and corners with two equivalent SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.61–1.68 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent BeO3F tetrahedra and corners with two equivalent SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.68 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, two equivalent Ca2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Na1+ and two Si4+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Ca2+, one Be2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+, one Ca2+, one Be2+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Na1+, one Ca2+, one Be2+, and one Si4+ atom. F1- is bonded in a 1-coordinate geometry to two equivalent Na1+, one Ca2+, and one Be2+ atom.