Materials Data on SrAl2SiN2O3 by Materials Project
SrSiAl2O3N2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to three N3- and six O2- atoms. There are a spread of Sr–N bond distances ranging from 2.84–3.23 Å. There are a spread of Sr–O bond distances ranging from 2.52–3.23 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to one N3- and three O2- atoms to form AlNO3 tetrahedra that share corners with two equivalent SiN3O tetrahedra and corners with three equivalent AlN2O2 tetrahedra. The Al–N bond length is 1.86 Å. There are a spread of Al–O bond distances ranging from 1.76–1.78 Å. In the second Al3+ site, Al3+ is bonded to two N3- and two O2- atoms to form AlN2O2 tetrahedra that share corners with three equivalent AlNO3 tetrahedra and corners with three equivalent SiN3O tetrahedra. There is one shorter (1.86 Å) and one longer (1.88 Å) Al–N bond length. There is one shorter (1.77 Å) and one longer (1.79 Å) Al–O bond length. Si4+ is bonded to three N3- and one O2- atom to form SiN3O tetrahedra that share corners with two equivalent SiN3O tetrahedra and corners with five AlNO3 tetrahedra. There are a spread of Si–N bond distances ranging from 1.73–1.75 Å. The Si–O bond length is 1.68 Å. There are two inequivalent N3- sites. In the first N3- site, N3- is bonded in a 3-coordinate geometry to one Sr2+, one Al3+, and two equivalent Si4+ atoms. In the second N3- site, N3- is bonded in a distorted trigonal planar geometry to two equivalent Sr2+, two Al3+, and one Si4+ atom. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Sr2+ and two Al3+ atoms to form distorted corner-sharing OSr2Al2 tetrahedra. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+, one Al3+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Sr2+ and two Al3+ atoms.