Materials Data on Nb3CuO8 by Materials Project
CuNb3O8 is Brookite-derived structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Nb–O bond distances ranging from 1.87–2.42 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three equivalent NbO6 octahedra and corners with four equivalent CuO6 octahedra. The corner-sharing octahedra tilt angles range from 44–59°. There are a spread of Nb–O bond distances ranging from 1.88–2.34 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one CuO6 octahedra, corners with five NbO6 octahedra, and edges with two equivalent CuO6 octahedra. The corner-sharing octahedra tilt angles range from 44–51°. There are a spread of Nb–O bond distances ranging from 1.89–2.18 Å. Cu1+ is bonded to six O2- atoms to form distorted CuO6 octahedra that share corners with five NbO6 octahedra and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Cu–O bond distances ranging from 2.10–2.47 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Nb5+ and one Cu1+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Nb5+ and one Cu1+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Nb5+ and one Cu1+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Nb5+ and one Cu1+ atom. In the seventh O2- site, O2- is bonded in a trigonal planar geometry to two Nb5+ and one Cu1+ atom. In the eighth O2- site, O2- is bonded in a trigonal planar geometry to two Nb5+ and one Cu1+ atom.