DOE OSTI2020
Mg14CeSn crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are seven inequivalent Mg sites. In the first Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with four equivalent CeMg10Sn2 cuboctahedra, corners with fourteen MgMg12 cuboctahedra, edges with fourteen MgCeMg10Sn cuboctahedra, faces with two equivalent SnCe2Mg10 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.28 Å. In the second Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with four equivalent SnCe2Mg10 cuboctahedra, corners with fourteen MgMg12 cuboctahedra, edges with eighteen MgCeMg10Sn cuboctahedra, faces with two equivalent CeMg10Sn2 cuboctahedra, and faces with twelve MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.18–3.28 Å. In the third Mg site, Mg is bonded to eight Mg, two equivalent Ce, and two equivalent Sn atoms to form distorted MgCe2Mg8Sn2 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with two equivalent CeMg10Sn2 cuboctahedra, edges with two equivalent SnCe2Mg10 cuboctahedra, edges with ten MgCe2Mg8Sn2 cuboctahedra, faces with two equivalent CeMg10Sn2 cuboctahedra, faces with two equivalent SnCe2Mg10 cuboctahedra, and faces with fourteen MgCe2Mg8Sn2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.19–3.29 Å. There are one shorter (3.26 Å) and one longer (3.29 Å) Mg–Ce bond lengths. There are one shorter (3.24 Å) and one longer (3.32 Å) Mg–Sn bond lengths. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with four equivalent CeMg10Sn2 cuboctahedra, corners with four equivalent SnCe2Mg10 cuboctahedra, corners with ten MgCe2Mg8Sn2 cuboctahedra, edges with fourteen MgMg12 cuboctahedra, and faces with eighteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.25 Å. In the fifth Mg site, Mg is bonded to ten Mg, one Ce, and one Sn atom to form distorted MgCeMg10Sn cuboctahedra that share corners with fourteen MgCeMg10Sn cuboctahedra, edges with two equivalent CeMg10Sn2 cuboctahedra, edges with two equivalent SnCe2Mg10 cuboctahedra, edges with twelve MgMg12 cuboctahedra, a faceface with one CeMg10Sn2 cuboctahedra, a faceface with one SnCe2Mg10 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.23–3.31 Å. The Mg–Ce bond length is 3.27 Å. The Mg–Sn bond length is 3.25 Å. In the sixth Mg site, Mg is bonded in a distorted single-bond geometry to eleven Mg and one Sn atom. Both Mg–Mg bond lengths are 3.24 Å. The Mg–Sn bond length is 3.23 Å. In the seventh Mg site, Mg is bonded to eleven Mg and one Ce atom to form MgCeMg11 cuboctahedra that share corners with fourteen MgCeMg10Sn cuboctahedra, edges with two equivalent CeMg10Sn2 cuboctahedra, edges with fourteen MgMg12 cuboctahedra, a faceface with one CeMg10Sn2 cuboctahedra, faces with three equivalent SnCe2Mg10 cuboctahedra, and faces with fourteen MgMg12 cuboctahedra. The Mg–Ce bond length is 3.27 Å. Ce is bonded to ten Mg and two equivalent Sn atoms to form CeMg10Sn2 cuboctahedra that share corners with six equivalent CeMg10Sn2 cuboctahedra, corners with twelve MgMg12 cuboctahedra, edges with two equivalent SnCe2Mg10 cuboctahedra, edges with sixteen MgCeMg10Sn cuboctahedra, faces with two equivalent SnCe2Mg10 cuboctahedra, and faces with twelve MgMg12 cuboctahedra. Both Ce–Sn bond lengths are 3.24 Å. Sn is bonded to ten Mg and two equivalent Ce atoms to form SnCe2Mg10 cuboctahedra that share corners with six equivalent SnCe2Mg10 cuboctahedra, corners with twelve MgMg12 cuboctahedra, edges with two equivalent CeMg10Sn2 cuboctahedra, edges with twelve MgCeMg10Sn cuboctahedra, faces with two equivalent CeMg10Sn2 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra.