DOE OSTI2020
Cu2V2O7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent V5+ sites. In the first V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with four equivalent CuO6 octahedra, corners with two equivalent CuO5 square pyramids, and a cornercorner with one VO4 tetrahedra. The corner-sharing octahedra tilt angles range from 43–70°. There are a spread of V–O bond distances ranging from 1.69–1.82 Å. In the second V5+ site, V5+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with three equivalent CuO6 octahedra, corners with three equivalent CuO5 square pyramids, and a cornercorner with one VO4 tetrahedra. The corner-sharing octahedra tilt angles range from 27–67°. There are a spread of V–O bond distances ranging from 1.70–1.85 Å. There are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded to five O2- atoms to form distorted CuO5 square pyramids that share corners with five VO4 tetrahedra and edges with two equivalent CuO5 square pyramids. There are a spread of Cu–O bond distances ranging from 1.90–2.40 Å. In the second Cu2+ site, Cu2+ is bonded to six O2- atoms to form distorted CuO6 octahedra that share corners with seven VO4 tetrahedra and edges with two equivalent CuO6 octahedra. There are a spread of Cu–O bond distances ranging from 1.91–2.55 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V5+ and two equivalent Cu2+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one V5+ and one Cu2+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one V5+ and two equivalent Cu2+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one V5+ and two equivalent Cu2+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one V5+ and one Cu2+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one V5+ and two equivalent Cu2+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two V5+ and one Cu2+ atom.