Materials Data on K3Na3Nb8(PO7)5 by Materials Project
K3Na3Nb8(PO7)5 crystallizes in the trigonal R32 space group. The structure is three-dimensional. K1+ is bonded in a 8-coordinate geometry to eleven O2- atoms. There are a spread of K–O bond distances ranging from 2.84–3.27 Å. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.63 Å. There are two inequivalent Nb+4.88+ sites. In the first Nb+4.88+ site, Nb+4.88+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with four NbO6 octahedra and corners with two PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 0–35°. There are a spread of Nb–O bond distances ranging from 1.91–2.13 Å. In the second Nb+4.88+ site, Nb+4.88+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three equivalent NbO6 octahedra and corners with three equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 35°. There are three shorter (1.92 Å) and three longer (2.16 Å) Nb–O bond lengths. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with four NbO6 octahedra. The corner-sharing octahedra tilt angles range from 48–51°. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share corners with three equivalent NbO6 octahedra. The corner-sharing octahedral tilt angles are 31°. There is one shorter (1.51 Å) and three longer (1.56 Å) P–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Nb+4.88+, and one P5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one K1+ and two Nb+4.88+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent K1+, one Nb+4.88+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a linear geometry to three equivalent K1+ and two equivalent Nb+4.88+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two equivalent Nb+4.88+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Na1+ and one P5+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one Nb+4.88+, and one P5+ atom.