Materials Data on FeCoAs4 by Materials Project
FeCoAs4 crystallizes in the monoclinic P2/m space group. The structure is three-dimensional. Fe2+ is bonded to six As1- atoms to form FeAs6 octahedra that share corners with eight equivalent CoAs6 octahedra and edges with two equivalent FeAs6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two shorter (2.34 Å) and four longer (2.37 Å) Fe–As bond lengths. Co2+ is bonded to six As1- atoms to form CoAs6 octahedra that share corners with eight equivalent FeAs6 octahedra and edges with two equivalent CoAs6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are two shorter (2.36 Å) and four longer (2.38 Å) Co–As bond lengths. There are two inequivalent As1- sites. In the first As1- site, As1- is bonded in a 4-coordinate geometry to two equivalent Fe2+ and one Co2+ atom. In the second As1- site, As1- is bonded in a 4-coordinate geometry to one Fe2+ and two equivalent Co2+ atoms.