Materials Data on SmMg2Cu9 by Materials Project

SmCu9Mg2 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Mg is bonded in a 12-coordinate geometry to twelve Cu atoms. There are a spread of Mg–Cu bond distances ranging from 2.89–2.95 Å. Sm is bonded in a distorted hexagonal planar geometry to eighteen Cu atoms. There are six shorter (2.90 Å) and twelve longer (3.25 Å) Sm–Cu bond lengths. There are four inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Sm and nine Cu atoms. There are six shorter (2.51 Å) and three longer (2.90 Å) Cu–Cu bond lengths. In the second Cu site, Cu is bonded to three equivalent Mg, two equivalent Sm, and seven Cu atoms to form a mixture of edge, face, and corner-sharing CuSm2Mg3Cu7 cuboctahedra. There are a spread of Cu–Cu bond distances ranging from 2.47–2.54 Å. In the third Cu site, Cu is bonded in a 12-coordinate geometry to three equivalent Sm and nine Cu atoms. In the fourth Cu site, Cu is bonded to six equivalent Mg and six equivalent Cu atoms to form CuMg6Cu6 cuboctahedra that share corners with twelve equivalent CuSm2Mg3Cu7 cuboctahedra, edges with six equivalent CuMg6Cu6 cuboctahedra, and faces with eighteen equivalent CuSm2Mg3Cu7 cuboctahedra.