Materials Data on MgAlO2F5 by Materials Project
MgAlO2F5 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Mg is bonded to two equivalent O and four equivalent F atoms to form MgO2F4 octahedra that share corners with four equivalent AlF6 octahedra. The corner-sharing octahedral tilt angles are 38°. Both Mg–O bond lengths are 2.19 Å. All Mg–F bond lengths are 1.96 Å. Al is bonded to six F atoms to form AlF6 octahedra that share corners with two equivalent AlF6 octahedra and corners with four equivalent MgO2F4 octahedra. The corner-sharing octahedra tilt angles range from 34–38°. There is four shorter (1.83 Å) and two longer (1.84 Å) Al–F bond length. O is bonded in a single-bond geometry to one Mg atom. There are two inequivalent F sites. In the first F site, F is bonded in a bent 150 degrees geometry to one Mg and one Al atom. In the second F site, F is bonded in a bent 150 degrees geometry to two equivalent Al atoms.