Materials Data on NaFe5O8 by Materials Project
NaFe5O8 is Spinel-like structured and crystallizes in the cubic P4_332 space group. The structure is three-dimensional. Na1+ is bonded to six equivalent O2- atoms to form NaO6 octahedra that share corners with six equivalent FeO4 tetrahedra and edges with six equivalent FeO6 octahedra. All Na–O bond lengths are 2.30 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent NaO6 octahedra and corners with nine equivalent FeO6 octahedra. The corner-sharing octahedra tilt angles range from 51–63°. There is three shorter (1.93 Å) and one longer (1.99 Å) Fe–O bond length. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with six equivalent FeO4 tetrahedra, edges with two equivalent NaO6 octahedra, and edges with four equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 2.02–2.09 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Na1+ and three Fe3+ atoms. In the second O2- site, O2- is bonded to four Fe3+ atoms to form distorted corner-sharing OFe4 trigonal pyramids.