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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CrFeAs by Materials Project

CrFeAs crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Cr is bonded in a 5-coordinate geometry to five As atoms. There are one shorter (2.50 Å) and four longer (2.60 Å) Cr–As bond lengths. Fe is bonded in a 4-coordinate geometry to four As atoms. There are two shorter (2.33 Å) and two longer (2.37 Å) Fe–As bond lengths. There are two inequivalent As sites. In the first As site, As is bonded in a distorted q6 geometry to three equivalent Cr and six equivalent Fe atoms. In the second As site, As is bonded in a 9-coordinate geometry to six equivalent Cr and three equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrFe3As2 by Materials Project

CrFe3As2 crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. Cr is bonded to eight Fe and four equivalent As atoms to form CrFe8As4 cuboctahedra that share corners with four equivalent CrFe8As4 cuboctahedra, faces with four equivalent CrFe8As4 cuboctahedra, and faces with four equivalent FeCr4Fe4As4 cuboctahedra. There are four shorter (2.59 Å) and four longer (2.69 Å) Cr–Fe bond lengths. All Cr–As bond lengths are 2.47 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to four equivalent Cr, four equivalent Fe, and four equivalent As atoms to form distorted FeCr4Fe4As4 cuboctahedra that share corners with four equivalent FeCr4Fe4As4 cuboctahedra, faces with four equivalent CrFe8As4 cuboctahedra, and faces with four equivalent FeCr4Fe4As4 cuboctahedra. All Fe–Fe bond lengths are 2.69 Å. All Fe–As bond lengths are 2.47 Å. In the second Fe site, Fe is bonded in a 5-coordinate geometry to two equivalent Cr, two equivalent Fe, and five equivalent As atoms. There are one shorter (2.44 Å) and four longer (2.61 Å) Fe–As bond lengths. As is bonded in a 9-coordinate geometry to two equivalent Cr and seven Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CrFeAs4 by Materials Project

CrFeAs4 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. Cr3+ is bonded to six As+1.50- atoms to form CrAs6 octahedra that share corners with eight equivalent FeAs6 octahedra and edges with two equivalent CrAs6 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are four shorter (2.49 Å) and two longer (2.50 Å) Cr–As bond lengths. Fe3+ is bonded to six As+1.50- atoms to form FeAs6 octahedra that share corners with eight equivalent CrAs6 octahedra and edges with two equivalent FeAs6 octahedra. The corner-sharing octahedra tilt angles range from 52–54°. There are two shorter (2.38 Å) and four longer (2.39 Å) Fe–As bond lengths. There are two inequivalent As+1.50- sites. In the first As+1.50- site, As+1.50- is bonded in a 4-coordinate geometry to one Cr3+ and two equivalent Fe3+ atoms. In the second As+1.50- site, As+1.50- is bonded in a 4-coordinate geometry to two equivalent Cr3+ and one Fe3+ atom.

36 MATERIALS SCIENCE↗