Materials Data on Fe2CoSe4 by Materials Project

Fe2CoSe4 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent FeSe6 octahedra, corners with six equivalent CoSe6 octahedra, edges with two equivalent FeSe6 octahedra, a faceface with one FeSe6 octahedra, and a faceface with one CoSe6 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are one shorter (2.44 Å) and five longer (2.48 Å) Fe–Se bond lengths. In the second Fe3+ site, Fe3+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent FeSe6 octahedra, edges with two equivalent FeSe6 octahedra, edges with four equivalent CoSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 51–52°. There are a spread of Fe–Se bond distances ranging from 2.37–2.49 Å. Co2+ is bonded to six Se2- atoms to form CoSe6 octahedra that share corners with six equivalent FeSe6 octahedra, edges with two equivalent CoSe6 octahedra, edges with four equivalent FeSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of Co–Se bond distances ranging from 2.36–2.51 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to two Fe3+ and two equivalent Co2+ atoms. In the second Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to three Fe3+ and one Co2+ atom. In the third Se2- site, Se2- is bonded in a 5-coordinate geometry to four Fe3+ and one Co2+ atom. In the fourth Se2- site, Se2- is bonded in a 5-coordinate geometry to three Fe3+ and two equivalent Co2+ atoms.