Materials Data on K5Nb16(O5F2)4 by Materials Project
K5Nb16(O5F2)4 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 9-coordinate geometry to four equivalent O2- and five F1- atoms. All K–O bond lengths are 2.98 Å. There are one shorter (2.60 Å) and four longer (2.96 Å) K–F bond lengths. In the second K1+ site, K1+ is bonded in a 1-coordinate geometry to four equivalent O2- and five F1- atoms. All K–O bond lengths are 3.06 Å. There are one shorter (2.51 Å) and four longer (2.96 Å) K–F bond lengths. In the third K1+ site, K1+ is bonded in a 9-coordinate geometry to four equivalent O2- and five F1- atoms. All K–O bond lengths are 2.88 Å. There are one shorter (2.69 Å) and four longer (2.96 Å) K–F bond lengths. There are seven inequivalent Nb+2.69+ sites. In the first Nb+2.69+ site, Nb+2.69+ is bonded to four equivalent O2- and one F1- atom to form corner-sharing NbO4F square pyramids. All Nb–O bond lengths are 2.09 Å. The Nb–F bond length is 2.12 Å. In the second Nb+2.69+ site, Nb+2.69+ is bonded to four equivalent O2- and one F1- atom to form corner-sharing NbO4F square pyramids. All Nb–O bond lengths are 2.09 Å. The Nb–F bond length is 2.20 Å. In the third Nb+2.69+ site, Nb+2.69+ is bonded to four equivalent O2- and one F1- atom to form corner-sharing NbO4F square pyramids. All Nb–O bond lengths are 2.09 Å. The Nb–F bond length is 2.10 Å. In the fourth Nb+2.69+ site, Nb+2.69+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Nb–O bond distances ranging from 2.09–2.13 Å. In the fifth Nb+2.69+ site, Nb+2.69+ is bonded to four equivalent O2- and one F1- atom to form corner-sharing NbO4F square pyramids. All Nb–O bond lengths are 2.09 Å. The Nb–F bond length is 2.12 Å. In the sixth Nb+2.69+ site, Nb+2.69+ is bonded to four equivalent O2- and one F1- atom to form corner-sharing NbO4F square pyramids. All Nb–O bond lengths are 2.09 Å. The Nb–F bond length is 2.00 Å. In the seventh Nb+2.69+ site, Nb+2.69+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Nb–O bond distances ranging from 2.09–2.13 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent K1+ and three Nb+2.69+ atoms. In the second O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent K1+ and three Nb+2.69+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to one K1+ and three Nb+2.69+ atoms. In the fourth O2- site, O2- is bonded in a T-shaped geometry to three Nb+2.69+ atoms. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four equivalent Nb+2.69+ atoms. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four equivalent Nb+2.69+ atoms. In the seventh O2- site, O2- is bonded in a square co-planar geometry to four equivalent Nb+2.69+ atoms. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted square co-planar geometry to three K1+ and one Nb+2.69+ atom. In the second F1- site, F1- is bonded in a linear geometry to one K1+ and one Nb+2.69+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to four equivalent K1+ and one Nb+2.69+ atom. In the fourth F1- site, F1- is bonded to five K1+ and one Nb+2.69+ atom to form distorted corner-sharing FK5Nb octahedra. The corner-sharing octahedral tilt angles are 1°. In the fifth F1- site, F1- is bonded in a distorted single-bond geometry to four equivalent K1+ and one Nb+2.69+ atom.