DOI: 10.17188/1284362
title: Materials Data on Na3MgAlSi7O18 by Materials Project

description: Na3MgAlSi7O18 is Esseneite-derived structured and crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.81 Å. In the second Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–2.73 Å. In the third Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.40–2.89 Å. In the fourth Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.35–2.78 Å. Mg2+ is bonded to six O2- atoms to form distorted MgO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent SiO6 octahedra. There are a spread of Mg–O bond distances ranging from 1.97–2.18 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.89–2.06 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent AlO6 octahedra. There is two shorter (1.85 Å) and four longer (1.98 Å) Al–O bond length. There are seven 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 MgO6 octahedra, corners with two equivalent SiO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 31–66°. There is two shorter (1.64 Å) and two longer (1.66 Å) Si–O bond length. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO6 octahedra, corners with two AlO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 32–60°. There is two shorter (1.64 Å) and two longer (1.65 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one AlO6 octahedra, a cornercorner with one SiO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 31–68°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO6 octahedra, corners with two equivalent MgO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 39–64°. There are a spread of Si–O bond distances ranging from 1.58–1.67 Å. In the fifth Si4+ site, Si4+ is bonded to six O2- atoms to form SiO6 octahedra that share corners with six SiO4 tetrahedra and edges with two equivalent MgO6 octahedra. There are a spread of Si–O bond distances ranging from 1.80–1.90 Å. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, corners with two AlO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–60°. There are a spread of Si–O bond distances ranging from 1.58–1.67 Å. In the seventh Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one MgO6 octahedra, a cornercorner with one AlO6 octahedra, a cornercorner with one SiO6 octahedra, and corners with two equivalent SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 34–65°. There are a spread of Si–O bond distances ranging from 1.61–1.67 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Mg2+, and two Si4+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Al3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mg2+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Mg2+, and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Al3+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+ and two Si4+ atoms. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Mg2+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, two Al3+, and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Mg2+, and two Si4+ atoms. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+ and two Si4+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Al3+, and one Si4+ atom. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Mg2+, and two Si4+ atoms. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms.