Materials Data on NaFeAsO4F by Materials Project
NaFeAsO4F 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 2.45–2.78 Å. The Na–F bond length is 2.25 Å. Fe3+ is bonded to four O2- and two equivalent F1- atoms to form FeO4F2 octahedra that share corners with two equivalent FeO4F2 octahedra and corners with four equivalent AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 40°. There are two shorter (2.00 Å) and two longer (2.04 Å) Fe–O bond lengths. Both Fe–F bond lengths are 1.99 Å. As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with four equivalent FeO4F2 octahedra. The corner-sharing octahedra tilt angles range from 40–54°. All As–O bond lengths are 1.73 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Fe3+, and one As5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Fe3+, and one As5+ atom. F1- is bonded in a distorted trigonal planar geometry to one Na1+ and two equivalent Fe3+ atoms.