Materials Data on Al2Ge(O2F)2 by Materials Project

Abstract

Al2Ge(O2F)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Al3+ is bonded to four O2- and two equivalent F1- atoms to form AlO4F2 octahedra that share corners with two equivalent AlO4F2 octahedra, corners with four equivalent GeO4 tetrahedra, and edges with two equivalent AlO4F2 octahedra. The corner-sharing octahedral tilt angles are 33°. There are a spread of Al–O bond distances ranging from 1.89–1.92 Å. There is one shorter (1.84 Å) and one longer (1.85 Å) Al–F bond length. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with eight equivalent AlO4F2 octahedra. The corner-sharing octahedra tilt angles range from 51–55°. There is three shorter (1.77 Å) and one longer (1.78 Å) Ge–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Ge4+ atom. F1- is bonded in a bent 150 degrees geometry to two equivalent Al3+ atoms.