Materials Data on Sr2Al2SiO7 by Materials Project
Sr2Al2SiO7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.49–3.06 Å. In the second Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.53–3.00 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 two equivalent AlO4 tetrahedra and corners with two equivalent SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.77–1.81 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.73–1.80 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three AlO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.67 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Sr2+, one Al3+, and one Si4+ atom. In the second O2- site, O2- is bonded to three Sr2+ and one Al3+ atom to form distorted corner-sharing OSr3Al tetrahedra. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Sr2+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+ and two Al3+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Sr2+, one Al3+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Sr2+, one Al3+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Sr2+ and two Al3+ atoms.