DOI: 10.17188/1279926
title: Materials Data on Al2SiO5 by Materials Project

description: Al2SiO5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share corners with two equivalent AlO5 square pyramids, a cornercorner with one SiO4 tetrahedra, a cornercorner with one AlO5 trigonal bipyramid, an edgeedge with one SiO6 octahedra, and edges with two equivalent AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.78–1.95 Å. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.79–2.05 Å. In the third Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share a cornercorner with one SiO6 octahedra, a cornercorner with one AlO5 square pyramid, a cornercorner with one SiO4 tetrahedra, a cornercorner with one AlO5 trigonal bipyramid, and edges with three AlO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 51°. There are a spread of Al–O bond distances ranging from 1.79–2.02 Å. In the fourth Al3+ site, Al3+ is bonded to five O2- atoms to form distorted AlO5 square pyramids that share corners with three equivalent SiO6 octahedra, corners with two equivalent SiO4 tetrahedra, and corners with five AlO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 31–50°. There are a spread of Al–O bond distances ranging from 1.78–2.17 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to six O2- atoms to form SiO6 octahedra that share corners with three equivalent AlO5 square pyramids, corners with two equivalent SiO4 tetrahedra, a cornercorner with one AlO5 trigonal bipyramid, an edgeedge with one SiO6 octahedra, an edgeedge with one SiO4 tetrahedra, and an edgeedge with one AlO5 trigonal bipyramid. There are a spread of Si–O bond distances ranging from 1.72–1.90 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent SiO6 octahedra, corners with two equivalent AlO5 square pyramids, corners with two AlO5 trigonal bipyramids, and an edgeedge with one SiO6 octahedra. The corner-sharing octahedra tilt angles range from 60–66°. There are a spread of Si–O bond distances ranging from 1.63–1.74 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Al3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to three Al3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to two Al3+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to one Al3+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a trigonal non-coplanar geometry to three Si4+ atoms. In the eighth O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Al3+ and two Si4+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Al3+ atoms.