Materials Data on SrAl2(SiO4)2 by Materials Project

Abstract

SrAl2Si2O8 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Sr2+ is bonded in a 1-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.30–3.11 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with three equivalent SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.73–1.82 Å. In the second Al3+ site, Al3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.68 Å) and two longer (1.72 Å) Al–O bond length. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. In the second Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Si–O bond distances ranging from 1.59–1.69 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Al3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sr2+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sr2+, one Al3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Sr2+ and one Al3+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Sr2+, one Al3+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to one Sr2+, one Al3+, and one Si4+ atom.