Materials Data on SrAlSi4N7 by Materials Project
SrAlSi4N7 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 5-coordinate geometry to five N3- atoms. There are a spread of Sr–N bond distances ranging from 2.44–2.80 Å. In the second Sr2+ site, Sr2+ is bonded in a 10-coordinate geometry to ten N3- atoms. There are a spread of Sr–N bond distances ranging from 2.59–3.31 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with four SiN4 tetrahedra and edges with two equivalent AlN4 tetrahedra. There are a spread of Al–N bond distances ranging from 1.81–1.86 Å. In the second Al3+ site, Al3+ is bonded to four N3- atoms to form AlN4 tetrahedra that share corners with four SiN4 tetrahedra and edges with two equivalent AlN4 tetrahedra. There are a spread of Al–N bond distances ranging from 1.83–1.87 Å. There are eight inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four N3- atoms to form corner-sharing SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.68–1.83 Å. In the second Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with two AlN4 tetrahedra and corners with six SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.66–1.79 Å. In the third Si4+ site, Si4+ is bonded to four N3- atoms to form corner-sharing SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.68–1.80 Å. In the fourth Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with two AlN4 tetrahedra and corners with six SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.68–1.80 Å. In the fifth Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with two AlN4 tetrahedra and corners with six SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.66–1.79 Å. In the sixth Si4+ site, Si4+ is bonded to four N3- atoms to form corner-sharing SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.70–1.82 Å. In the seventh Si4+ site, Si4+ is bonded to four N3- atoms to form corner-sharing SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.73–1.80 Å. In the eighth Si4+ site, Si4+ is bonded to four N3- atoms to form SiN4 tetrahedra that share corners with two AlN4 tetrahedra and corners with six SiN4 tetrahedra. There are a spread of Si–N bond distances ranging from 1.68–1.79 Å. There are fourteen inequivalent N3- sites. In the first N3- site, N3- is bonded in a trigonal planar geometry to one Sr2+ and three Si4+ atoms. In the second N3- site, N3- is bonded in a distorted trigonal planar geometry to one Sr2+ and three Si4+ atoms. In the third N3- site, N3- is bonded in a distorted trigonal planar geometry to one Sr2+ and three Si4+ atoms. In the fourth N3- site, N3- is bonded in a 2-coordinate geometry to two equivalent Sr2+ and two Si4+ atoms. In the fifth N3- site, N3- is bonded in a distorted trigonal planar geometry to one Sr2+ and three Si4+ atoms. In the sixth N3- site, N3- is bonded in a distorted rectangular see-saw-like geometry to one Sr2+, two Al3+, and one Si4+ atom. In the seventh N3- site, N3- is bonded in a 4-coordinate geometry to one Sr2+ and three Si4+ atoms. In the eighth N3- site, N3- is bonded in a 3-coordinate geometry to two equivalent Sr2+, two Al3+, and one Si4+ atom. In the ninth N3- site, N3- is bonded in a trigonal planar geometry to three Si4+ atoms. In the tenth N3- site, N3- is bonded in a 3-coordinate geometry to two Al3+ and one Si4+ atom. In the eleventh N3- site, N3- is bonded to one Sr2+, two Al3+, and one Si4+ atom to form corner-sharing NSrAl2Si tetrahedra. In the twelfth N3- site, N3- is bonded in a distorted trigonal planar geometry to one Sr2+ and three Si4+ atoms. In the thirteenth N3- site, N3- is bonded to one Sr2+ and three Si4+ atoms to form distorted corner-sharing NSrSi3 trigonal pyramids. In the fourteenth N3- site, N3- is bonded in a 2-coordinate geometry to two equivalent Sr2+ and two Si4+ atoms.