Materials Data on NaNb6O15F by Materials Project
NaNb6O15F crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Na1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Na–O bond distances ranging from 2.56–2.78 Å. There are four inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and an edgeedge with one NbO5F2 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 6–47°. There are a spread of Nb–O bond distances ranging from 1.93–2.17 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with six NbO6 octahedra and an edgeedge with one NbO5F2 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 15–42°. There are a spread of Nb–O bond distances ranging from 1.91–2.26 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and an edgeedge with one NbO5F2 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 4–47°. There are a spread of Nb–O bond distances ranging from 1.98–2.05 Å. In the fourth Nb5+ site, Nb5+ is bonded to five O2- and two equivalent F1- atoms to form NbO5F2 pentagonal bipyramids that share corners with two equivalent NbO5F2 pentagonal bipyramids and edges with five NbO6 octahedra. There are a spread of Nb–O bond distances ranging from 2.04–2.07 Å. Both Nb–F bond lengths are 1.98 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded to two equivalent Na1+ and two equivalent Nb5+ atoms to form distorted corner-sharing ONa2Nb2 tetrahedra. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to three Nb5+ atoms. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Nb5+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to one Na1+ and two equivalent Nb5+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Nb5+ atoms. In the eighth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na1+ and two Nb5+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. F1- is bonded in a linear geometry to two equivalent Nb5+ atoms.