DOE OSTI2020
MgCd is beta-derived structured and crystallizes in the trigonal P3m1 space group. The structure is three-dimensional. there are three inequivalent Mg sites. In the first Mg site, Mg is bonded to six equivalent Mg and six Cd atoms to form distorted MgMg6Cd6 cuboctahedra that share corners with six equivalent CdMg3Cd9 cuboctahedra, corners with twelve MgMg6Cd6 cuboctahedra, edges with six equivalent MgMg6Cd6 cuboctahedra, edges with twelve CdMg3Cd9 cuboctahedra, faces with seven MgMg6Cd6 cuboctahedra, and faces with thirteen CdMg3Cd9 cuboctahedra. All Mg–Mg bond lengths are 3.16 Å. There are three shorter (3.15 Å) and three longer (3.16 Å) Mg–Cd bond lengths. In the second Mg site, Mg is bonded to nine Mg and three equivalent Cd atoms to form distorted MgMg9Cd3 cuboctahedra that share corners with six equivalent MgMg9Cd3 cuboctahedra, corners with twelve CdMg3Cd9 cuboctahedra, edges with six equivalent CdMg3Cd9 cuboctahedra, edges with twelve MgMg9Cd3 cuboctahedra, faces with eight CdMg3Cd9 cuboctahedra, and faces with twelve MgMg9Cd3 cuboctahedra. There are six shorter (3.16 Å) and three longer (3.18 Å) Mg–Mg bond lengths. All Mg–Cd bond lengths are 3.14 Å. In the third Mg site, Mg is bonded to nine Mg and three equivalent Cd atoms to form distorted MgMg9Cd3 cuboctahedra that share corners with six equivalent CdMg3Cd9 cuboctahedra, corners with twelve MgMg6Cd6 cuboctahedra, edges with six equivalent CdMg6Cd6 cuboctahedra, edges with twelve MgMg9Cd3 cuboctahedra, faces with seven CdMg3Cd9 cuboctahedra, and faces with thirteen MgMg6Cd6 cuboctahedra. All Mg–Mg bond lengths are 3.16 Å. All Mg–Cd bond lengths are 3.16 Å. There are three inequivalent Cd sites. In the first Cd site, Cd is bonded to three equivalent Mg and nine Cd atoms to form distorted CdMg3Cd9 cuboctahedra that share corners with six equivalent MgMg9Cd3 cuboctahedra, corners with twelve CdMg3Cd9 cuboctahedra, edges with six equivalent MgMg6Cd6 cuboctahedra, edges with twelve CdMg3Cd9 cuboctahedra, faces with seven MgMg6Cd6 cuboctahedra, and faces with thirteen CdMg3Cd9 cuboctahedra. There are six shorter (3.16 Å) and three longer (3.19 Å) Cd–Cd bond lengths. In the second Cd site, Cd is bonded to three equivalent Mg and nine Cd atoms to form distorted CdMg3Cd9 cuboctahedra that share corners with six equivalent CdMg3Cd9 cuboctahedra, corners with twelve MgMg6Cd6 cuboctahedra, edges with six equivalent MgMg9Cd3 cuboctahedra, edges with twelve CdMg3Cd9 cuboctahedra, faces with eight MgMg6Cd6 cuboctahedra, and faces with twelve CdMg3Cd9 cuboctahedra. All Cd–Cd bond lengths are 3.16 Å. In the third Cd site, Cd is bonded to six Mg and six equivalent Cd atoms to form CdMg6Cd6 cuboctahedra that share corners with six equivalent MgMg9Cd3 cuboctahedra, corners with twelve CdMg3Cd9 cuboctahedra, edges with six equivalent CdMg6Cd6 cuboctahedra, edges with twelve MgMg6Cd6 cuboctahedra, faces with seven CdMg3Cd9 cuboctahedra, and faces with thirteen MgMg6Cd6 cuboctahedra. All Cd–Cd bond lengths are 3.16 Å.