Materials Data on Al2SiO5 by Materials Project
Al2SiO5 crystallizes in the orthorhombic Pnnm 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, corners with four equivalent AlO5 trigonal bipyramids, and edges with two equivalent AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.84–2.11 Å. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share corners with four equivalent AlO6 octahedra, corners with four equivalent SiO4 tetrahedra, and an edgeedge with one AlO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 49–58°. There are a spread of Al–O bond distances ranging from 1.83–1.91 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four equivalent AlO6 octahedra and corners with four equivalent AlO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 55–69°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to two Al3+ and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Si4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Si4+ atom.