Materials Data on Nb9P2O25 by Materials Project
Nb9P2O25 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are three inequivalent Nb+4.44+ sites. In the first Nb+4.44+ site, Nb+4.44+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. There are two shorter (1.94 Å) and four longer (2.06 Å) Nb–O bond lengths. In the second Nb+4.44+ site, Nb+4.44+ is bonded to six O2- atoms to form a mixture of distorted corner and edge-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 1–30°. There are a spread of Nb–O bond distances ranging from 1.85–2.37 Å. In the third Nb+4.44+ site, Nb+4.44+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with four NbO6 octahedra, corners with two equivalent PO4 tetrahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 8–32°. There are a spread of Nb–O bond distances ranging from 1.85–2.37 Å. P5+ is bonded to four equivalent O2- atoms to form PO4 tetrahedra that share corners with four equivalent NbO6 octahedra and edges with two equivalent PO4 tetrahedra. The corner-sharing octahedral tilt angles are 48°. All P–O bond lengths are 1.90 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Nb+4.44+ and two equivalent P5+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Nb+4.44+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two Nb+4.44+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two Nb+4.44+ atoms. The O–Nb bond length is 1.85 Å. In the fifth O2- site, O2- is bonded in a linear geometry to two Nb+4.44+ atoms. The O–Nb bond length is 1.85 Å. In the sixth O2- site, O2- is bonded in a linear geometry to two Nb+4.44+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+4.44+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to three Nb+4.44+ atoms. In the ninth O2- site, O2- is bonded in a linear geometry to two Nb+4.44+ atoms.