DOI: 10.17188/1715247
title: Materials Data on Al4B2O9 by Materials Project

description: Al4B2O9 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are seven inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to five O2- atoms to form distorted AlO5 trigonal bipyramids that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO5 tetrahedra, corners with two equivalent BO4 tetrahedra, a cornercorner with one AlO5 trigonal bipyramid, edges with two equivalent AlO6 octahedra, and an edgeedge with one AlO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 52°. There are a spread of Al–O bond distances ranging from 1.78–2.24 Å. In the second Al3+ site, Al3+ is bonded to five O2- atoms to form distorted AlO5 tetrahedra that share corners with two equivalent AlO6 octahedra, a cornercorner with one AlO5 trigonal bipyramid, edges with two equivalent AlO6 octahedra, and an edgeedge with one AlO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 48°. There are a spread of Al–O bond distances ranging from 1.73–2.33 Å. In the third Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share corners with four AlO6 octahedra, corners with two equivalent BO4 tetrahedra, a cornercorner with one AlO5 trigonal bipyramid, and an edgeedge with one AlO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 62–68°. There are a spread of Al–O bond distances ranging from 1.79–1.90 Å. In the fourth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent BO4 tetrahedra, corners with two equivalent AlO5 trigonal bipyramids, edges with two equivalent AlO6 octahedra, and edges with two equivalent AlO5 trigonal bipyramids. There are a spread of Al–O bond distances ranging from 1.87–1.97 Å. In the fifth Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share a cornercorner with one AlO5 tetrahedra, a cornercorner with one BO4 tetrahedra, corners with two AlO5 trigonal bipyramids, edges with two equivalent AlO6 octahedra, and an edgeedge with one AlO5 trigonal bipyramid. There are a spread of Al–O bond distances ranging from 1.82–2.10 Å. In the sixth Al3+ site, Al3+ is bonded to five O2- atoms to form AlO5 trigonal bipyramids that share corners with two equivalent AlO6 octahedra, edges with two equivalent AlO6 octahedra, an edgeedge with one AlO5 tetrahedra, and an edgeedge with one AlO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 50°. There are a spread of Al–O bond distances ranging from 1.82–1.97 Å. In the seventh Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO5 trigonal bipyramids, edges with two equivalent AlO6 octahedra, and edges with two equivalent AlO5 tetrahedra. There are a spread of Al–O bond distances ranging from 1.83–1.97 Å. There are four inequivalent B3+ sites. In the first B3+ site, B3+ is bonded to four O2- atoms to form BO4 tetrahedra that share corners with four AlO6 octahedra and corners with four AlO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 54–61°. There are a spread of B–O bond distances ranging from 1.45–1.49 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.39 Å. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.37 Å) and two longer (1.41 Å) B–O bond length. In the fourth B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.37 Å) and two longer (1.39 Å) B–O bond length. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to three Al3+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one B3+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Al3+ and one B3+ atom. In the fourth O2- site, O2- is bonded to four Al3+ atoms to form distorted corner-sharing OAl4 trigonal pyramids. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to two Al3+ and one B3+ atom. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent Al3+ and one B3+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Al3+ and one B3+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Al3+ atoms. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one B3+ atom. In the tenth O2- site, O2- is bonded in a trigonal planar geometry to two Al3+ and one B3+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Al3+ and one B3+ atom. In the twelfth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to four Al3+ atoms. In the thirteenth O2- site, O2- is bonded to four Al3+ atoms to form corner-sharing OAl4 trigonal pyramids. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one B3+ atom.