DOE OSTI2020
CoBi6(SO8)2 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. Co4+ is bonded to six O2- atoms to form distorted CoO6 octahedra that share corners with four equivalent SO4 tetrahedra. There are a spread of Co–O bond distances ranging from 1.94–2.45 Å. There are three inequivalent Bi4+ sites. In the first Bi4+ site, Bi4+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Bi–O bond distances ranging from 2.22–2.30 Å. In the second Bi4+ site, Bi4+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Bi–O bond distances ranging from 2.22–2.52 Å. In the third Bi4+ site, Bi4+ is bonded in a 4-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.17–3.00 Å. S2+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with two equivalent CoO6 octahedra. The corner-sharing octahedra tilt angles range from 23–31°. There are a spread of S–O bond distances ranging from 1.47–1.52 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to four Bi4+ atoms to form distorted edge-sharing OBi4 tetrahedra. In the second O2- site, O2- is bonded to four Bi4+ atoms to form edge-sharing OBi4 tetrahedra. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Co4+ and one S2+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Co4+, one Bi4+, and one S2+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one S2+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to one Bi4+ and one S2+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Co4+ and two Bi4+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to four Bi4+ atoms. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to four Bi4+ atoms.