Materials Data on Al2Si2Pb2O9 by Materials Project
Al2Pb2Si2O9 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. there are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with four equivalent SiO4 tetrahedra and edges with two equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.87–2.00 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with four equivalent SiO4 tetrahedra and edges with two equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.86–2.04 Å. Pb2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Pb–O bond distances ranging from 2.41–3.11 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four AlO6 octahedra and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–57°. There are a spread of Si–O bond distances ranging from 1.63–1.67 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Al3+, two equivalent Pb2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Al3+, two equivalent Pb2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to two Al3+ and two equivalent Pb2+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Pb2+ and two equivalent Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one Si4+ atom.