Materials Data on Nb9As2O25 by Materials Project

Abstract

Nb9As2O25 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are two shorter (1.99 Å) and four longer (2.03 Å) Nb–O bond lengths. In the second Nb5+ site, Nb5+ 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 2–29°. There are a spread of Nb–O bond distances ranging from 1.87–2.38 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with four NbO6 octahedra, corners with two equivalent AsO4 tetrahedra, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 8–30°. There are a spread of Nb–O bond distances ranging from 1.86–2.40 Å. As+2.50+ is bonded to four equivalent O2- atoms to form distorted AsO4 tetrahedra that share corners with four equivalent NbO6 octahedra and edges with two equivalent AsO4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. All As–O bond lengths are 2.06 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Nb5+ and two equivalent As+2.50+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. The O–Nb bond length is 1.87 Å. In the third O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the fourth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. The O–Nb bond length is 1.87 Å. In the sixth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. There is one shorter (1.87 Å) and one longer (2.03 Å) O–Nb bond length. In the seventh O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to three Nb5+ atoms. In the tenth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms.