DOE OSTI2020
UCo5 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent U sites. In the first U site, U is bonded in a 12-coordinate geometry to fifteen Co atoms. There are a spread of U–Co bond distances ranging from 2.77–2.97 Å. In the second U site, U is bonded in a distorted hexagonal planar geometry to eighteen Co atoms. There are six shorter (2.74 Å) and twelve longer (3.12 Å) U–Co bond lengths. There are five inequivalent Co sites. In the first Co site, Co is bonded to four U and eight Co atoms to form a mixture of distorted corner, edge, and face-sharing CoU4Co8 cuboctahedra. There are a spread of Co–Co bond distances ranging from 2.32–2.97 Å. In the second Co site, Co is bonded to two equivalent U and ten Co atoms to form a mixture of corner, edge, and face-sharing CoU2Co10 cuboctahedra. There are six shorter (2.37 Å) and four longer (2.68 Å) Co–Co bond lengths. In the third Co site, Co is bonded to three equivalent U and nine Co atoms to form distorted CoU3Co9 cuboctahedra that share corners with eighteen CoU4Co8 cuboctahedra, edges with six equivalent CoU3Co9 cuboctahedra, and faces with nineteen CoU4Co8 cuboctahedra. All Co–Co bond lengths are 2.82 Å. In the fourth Co site, Co is bonded to three equivalent U and nine Co atoms to form distorted CoU3Co9 cuboctahedra that share corners with eighteen CoU4Co8 cuboctahedra, edges with six equivalent CoU3Co9 cuboctahedra, and faces with twenty-two CoU4Co8 cuboctahedra. All Co–Co bond lengths are 2.74 Å. In the fifth Co site, Co is bonded in a 4-coordinate geometry to three equivalent U and thirteen Co atoms. The Co–Co bond length is 2.52 Å.