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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Cr(FeSe2)2 by Materials Project

Cr(FeSe2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with twelve equivalent FeSe6 octahedra, edges with two equivalent CrSe6 octahedra, and faces with two equivalent FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are two shorter (2.53 Å) and four longer (2.56 Å) Cr–Se bond lengths. Fe+2.50+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with six equivalent CrSe6 octahedra, edges with six equivalent FeSe6 octahedra, and a faceface with one CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 53–56°. There are a spread of Fe–Se bond distances ranging from 2.40–2.67 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent Cr3+ and three equivalent Fe+2.50+ atoms. In the second Se2- site, Se2- is bonded in a 4-coordinate geometry to one Cr3+ and three equivalent Fe+2.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr2FeSe4 by Materials Project

FeCr2Se4 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Cr3+ is bonded to six Se2- atoms to form CrSe6 octahedra that share corners with six equivalent FeSe6 octahedra, edges with six equivalent CrSe6 octahedra, and a faceface with one FeSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are a spread of Cr–Se bond distances ranging from 2.51–2.60 Å. Fe2+ is bonded to six Se2- atoms to form FeSe6 octahedra that share corners with twelve equivalent CrSe6 octahedra, edges with two equivalent FeSe6 octahedra, and faces with two equivalent CrSe6 octahedra. The corner-sharing octahedra tilt angles range from 50–51°. There are two shorter (2.52 Å) and four longer (2.59 Å) Fe–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to three equivalent Cr3+ and one Fe2+ atom. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to three equivalent Cr3+ and two equivalent Fe2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cr(FeSe2)2 by Materials Project

Cr(FeSe2)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Cr3+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Cr–Se bond distances ranging from 2.45–2.51 Å. There are two inequivalent Fe+2.50+ sites. In the first Fe+2.50+ site, Fe+2.50+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of Fe–Se bond distances ranging from 2.36–2.50 Å. In the second Fe+2.50+ site, Fe+2.50+ is bonded in a distorted pentagonal planar geometry to five Se2- atoms. There are a spread of Fe–Se bond distances ranging from 2.35–2.57 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to one Cr3+ and two Fe+2.50+ atoms. In the second Se2- site, Se2- is bonded to one Cr3+ and three Fe+2.50+ atoms to form a mixture of distorted edge and corner-sharing SeCrFe3 tetrahedra. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to one Cr3+ and two Fe+2.50+ atoms. In the fourth Se2- site, Se2- is bonded to one Cr3+ and three Fe+2.50+ atoms to form a mixture of distorted edge and corner-sharing SeCrFe3 tetrahedra.

36 MATERIALS SCIENCE↗