DOE OSTI2020
VMn2O4 is Spinel-like structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are two inequivalent V4+ sites. In the first V4+ site, V4+ is bonded to six O2- atoms to form VO6 octahedra that share corners with three equivalent VO4 tetrahedra, corners with three equivalent MnO4 tetrahedra, and edges with six equivalent MnO6 octahedra. There are three shorter (1.94 Å) and three longer (2.09 Å) V–O bond lengths. In the second V4+ site, V4+ is bonded to four O2- atoms to form VO4 tetrahedra that share corners with three equivalent VO6 octahedra and corners with nine equivalent MnO6 octahedra. The corner-sharing octahedra tilt angles range from 55–57°. There is one shorter (1.93 Å) and three longer (1.96 Å) V–O bond length. There are two inequivalent Mn2+ sites. In the first Mn2+ site, Mn2+ is bonded to six O2- atoms to form MnO6 octahedra that share corners with three equivalent VO4 tetrahedra, corners with three equivalent MnO4 tetrahedra, edges with two equivalent VO6 octahedra, and edges with four equivalent MnO6 octahedra. There are a spread of Mn–O bond distances ranging from 2.06–2.20 Å. In the second Mn2+ site, Mn2+ is bonded to four O2- atoms to form MnO4 tetrahedra that share corners with three equivalent VO6 octahedra and corners with nine equivalent MnO6 octahedra. The corner-sharing octahedra tilt angles range from 52–60°. There are one shorter (2.02 Å) and three longer (2.05 Å) Mn–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a rectangular see-saw-like geometry to one V4+ and three Mn2+ atoms. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one V4+ and three equivalent Mn2+ atoms. In the third O2- site, O2- is bonded in a rectangular see-saw-like geometry to two V4+ and two equivalent Mn2+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal pyramidal geometry to four Mn2+ atoms.