DOE OSTI2020
SmCu5Sn crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Sm is bonded in a 6-coordinate geometry to fifteen Cu and four equivalent Sn atoms. There are a spread of Sm–Cu bond distances ranging from 2.91–3.37 Å. There are two shorter (3.30 Å) and two longer (3.40 Å) Sm–Sn bond lengths. There are four inequivalent Cu sites. In the first Cu site, Cu is bonded to three equivalent Sm, seven Cu, and two equivalent Sn atoms to form a mixture of corner, edge, and face-sharing CuSm3Cu7Sn2 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.51–2.58 Å. Both Cu–Sn bond lengths are 2.82 Å. In the second Cu site, Cu is bonded to three equivalent Sm, seven Cu, and two equivalent Sn atoms to form a mixture of corner, edge, and face-sharing CuSm3Cu7Sn2 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.50–2.55 Å. There are one shorter (2.77 Å) and one longer (2.80 Å) Cu–Sn bond lengths. In the third Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Sm, six Cu, and one Sn atom. The Cu–Cu bond length is 3.06 Å. The Cu–Sn bond length is 2.80 Å. In the fourth Cu site, Cu is bonded in a 4-coordinate geometry to three equivalent Sm, five Cu, and three equivalent Sn atoms. There are one shorter (2.65 Å) and two longer (3.04 Å) Cu–Sn bond lengths. Sn is bonded in a 1-coordinate geometry to four equivalent Sm and ten Cu atoms.