Materials Data on NaAlAsO4F by Materials Project
NaAlAsO4F crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded in a 7-coordinate geometry to six O2- and one F1- atom. There are a spread of Na–O bond distances ranging from 2.42–2.60 Å. The Na–F bond length is 2.27 Å. Al3+ is bonded to four O2- and two equivalent F1- atoms to form AlO4F2 octahedra that share corners with two equivalent AlO4F2 octahedra and corners with four equivalent AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. There is two shorter (1.90 Å) and two longer (1.91 Å) Al–O bond length. Both Al–F bond lengths are 1.87 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four equivalent AlO4F2 octahedra. The corner-sharing octahedra tilt angles range from 37–54°. There is two shorter (1.71 Å) and two longer (1.72 Å) As–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Al3+, and one As5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Al3+, and one As5+ atom. F1- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Al3+ atoms.