Materials Data on UCrFe by Materials Project
UCrFe is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. U is bonded in a 4-coordinate geometry to two equivalent U, six equivalent Cr, and six equivalent Fe atoms. Both U–U bond lengths are 2.78 Å. There are four shorter (2.94 Å) and two longer (3.13 Å) U–Cr bond lengths. There are four shorter (2.77 Å) and two longer (3.02 Å) U–Fe bond lengths. Cr is bonded to six equivalent U, two equivalent Cr, and four equivalent Fe atoms to form distorted CrU6Cr2Fe4 cuboctahedra that share corners with eight equivalent FeU6Cr4Fe2 cuboctahedra, corners with ten equivalent CrU6Cr2Fe4 cuboctahedra, edges with six equivalent CrU6Cr2Fe4 cuboctahedra, faces with six equivalent CrU6Cr2Fe4 cuboctahedra, and faces with twelve equivalent FeU6Cr4Fe2 cuboctahedra. Both Cr–Cr bond lengths are 2.22 Å. All Cr–Fe bond lengths are 2.54 Å. Fe is bonded to six equivalent U, four equivalent Cr, and two equivalent Fe atoms to form FeU6Cr4Fe2 cuboctahedra that share corners with eight equivalent CrU6Cr2Fe4 cuboctahedra, corners with ten equivalent FeU6Cr4Fe2 cuboctahedra, edges with six equivalent FeU6Cr4Fe2 cuboctahedra, faces with six equivalent FeU6Cr4Fe2 cuboctahedra, and faces with twelve equivalent CrU6Cr2Fe4 cuboctahedra. Both Fe–Fe bond lengths are 2.59 Å.