Materials Data on Al2Si2H4O9 by Materials Project

Abstract

Al2Si2O5(OH)4 crystallizes in the monoclinic Cc space group. The structure is two-dimensional and consists of eight hydrogen molecules and two Al2Si2HO9 sheets oriented in the (0, 0, 1) direction. In each Al2Si2HO9 sheet, there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Al–O bond distances ranging from 1.68–1.90 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form distorted AlO4 trigonal pyramids that share a cornercorner with one SiO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.71–2.02 Å. 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 SiO4 tetrahedra and a cornercorner with one AlO4 trigonal pyramid. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.66 Å. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two Si4+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to two Si4+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Si4+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to one Al3+ and one Si4+ atom. In the fifth O2- site, O2- is bonded in a water-like geometry to one Si4+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Al3+ and one O2- atom. The O–O bond length is 1.38 Å. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Al3+ and one O2- atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to two Al3+ atoms. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to two Al3+ atoms.