DOE OSTI2020
Sr3FeCo(O2Cl)2 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five Cl1- atoms. All Sr–O bond lengths are 2.63 Å. There are four shorter (3.08 Å) and one longer (3.25 Å) Sr–Cl bond lengths. In the second Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to four equivalent O2- and five Cl1- atoms. All Sr–O bond lengths are 2.63 Å. There are four shorter (3.14 Å) and one longer (3.41 Å) Sr–Cl bond lengths. In the third Sr2+ site, Sr2+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.64 Å) and four longer (2.73 Å) Sr–O bond lengths. Fe2+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent O2- and one Cl1- atom. All Fe–O bond lengths are 2.05 Å. The Fe–Cl bond length is 2.98 Å. Co2+ is bonded to four equivalent O2- and one Cl1- atom to form corner-sharing CoClO4 square pyramids. All Co–O bond lengths are 2.05 Å. The Co–Cl bond length is 2.66 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four Sr2+ and two equivalent Fe2+ atoms to form distorted OSr4Fe2 octahedra that share corners with eight OSr4Co2 octahedra, edges with three OSr4Co2 octahedra, and faces with four equivalent OSr4Fe2 octahedra. The corner-sharing octahedra tilt angles range from 2–65°. In the second O2- site, O2- is bonded to four Sr2+ and two equivalent Co2+ atoms to form a mixture of face, edge, and corner-sharing OSr4Co2 octahedra. The corner-sharing octahedra tilt angles range from 2–65°. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 6-coordinate geometry to five Sr2+ and one Fe2+ atom. In the second Cl1- site, Cl1- is bonded in a 6-coordinate geometry to five Sr2+ and one Co2+ atom.