Materials Data on Co9Se8 by Materials Project
Co9Se8 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Co+1.78+ sites. In the first Co+1.78+ site, Co+1.78+ is bonded to six equivalent Se2- atoms to form corner-sharing CoSe6 octahedra. All Co–Se bond lengths are 2.44 Å. In the second Co+1.78+ site, Co+1.78+ is bonded to four Se2- atoms to form CoSe4 tetrahedra that share corners with three equivalent CoSe6 octahedra, corners with six equivalent CoSe4 tetrahedra, and edges with three equivalent CoSe4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. There are one shorter (2.27 Å) and three longer (2.32 Å) Co–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a tetrahedral geometry to four equivalent Co+1.78+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to five Co+1.78+ atoms.