DOI: 10.17188/1281118
title: Materials Data on Na8Si7O18 by Materials Project

description: Na8Si7O18 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.22–3.03 Å. In the second Na1+ site, Na1+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Na–O bond distances ranging from 2.17–2.26 Å. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.88 Å. In the fourth Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.29–2.89 Å. In the fifth Na1+ site, Na1+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.27–2.50 Å. In the sixth Na1+ site, Na1+ is bonded in a distorted rectangular see-saw-like geometry to four O2- atoms. There are a spread of Na–O bond distances ranging from 2.18–2.58 Å. In the seventh Na1+ site, Na1+ is bonded in a distorted T-shaped geometry to three O2- atoms. There are a spread of Na–O bond distances ranging from 2.18–2.36 Å. In the eighth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.25–2.55 Å. There are seven inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded in a bent 120 degrees geometry to two O2- atoms. Both Si–O bond lengths are 1.63 Å. In the second Si4+ site, Si4+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Si–O bond distances ranging from 1.57–1.70 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.59–1.74 Å. In the fourth Si4+ site, Si4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.57 Å) and one longer (1.64 Å) Si–O bond length. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.58–1.71 Å. In the sixth Si4+ site, Si4+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Si–O bond distances ranging from 1.61–1.83 Å. In the seventh Si4+ site, Si4+ is bonded in a water-like geometry to two O2- atoms. There is one shorter (1.56 Å) and one longer (1.66 Å) Si–O bond length. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one Si4+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three Na1+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to two Na1+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Na1+ and one Si4+ atom. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Si4+ atoms. In the ninth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Na1+ and one Si4+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to four Na1+ and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Si4+ atoms. In the twelfth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one O2- atom. The O–O bond length is 1.48 Å. In the thirteenth O2- site, O2- is bonded in a distorted single-bond geometry to two Na1+, one Si4+, and one O2- atom. In the fourteenth O2- site, O2- is bonded in a bent 120 degrees geometry to two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two Si4+ atoms. In the sixteenth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and one Si4+ atom. In the seventeenth O2- site, O2- is bonded in a distorted single-bond geometry to one Na1+ and one Si4+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms.