DOE OSTI2020
Mg6LaBi crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are four inequivalent Mg sites. In the first Mg site, Mg is bonded to eight Mg, two equivalent La, and two equivalent Bi atoms to form MgLa2Mg8Bi2 cuboctahedra that share corners with four equivalent LaMg10Bi2 cuboctahedra, corners with four equivalent BiLa2Mg10 cuboctahedra, corners with ten equivalent MgLa2Mg8Bi2 cuboctahedra, edges with two equivalent MgLa2Mg8Bi2 cuboctahedra, edges with two equivalent LaMg10Bi2 cuboctahedra, edges with two equivalent BiLa2Mg10 cuboctahedra, faces with two equivalent LaMg10Bi2 cuboctahedra, faces with two equivalent BiLa2Mg10 cuboctahedra, and faces with four equivalent MgLa2Mg8Bi2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.29 Å. There are one shorter (3.45 Å) and one longer (3.59 Å) Mg–La bond lengths. There are one shorter (3.47 Å) and one longer (3.57 Å) Mg–Bi bond lengths. In the second Mg site, Mg is bonded in a 10-coordinate geometry to six Mg, two equivalent La, and two equivalent Bi atoms. There are a spread of Mg–Mg bond distances ranging from 3.18–3.32 Å. Both Mg–La bond lengths are 3.40 Å. Both Mg–Bi bond lengths are 3.35 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to eight Mg and two equivalent La atoms. Both Mg–Mg bond lengths are 3.19 Å. Both Mg–La bond lengths are 3.40 Å. In the fourth Mg site, Mg is bonded in a 2-coordinate geometry to eight Mg and two equivalent Bi atoms. Both Mg–Bi bond lengths are 3.40 Å. La is bonded to ten Mg and two equivalent Bi atoms to form distorted LaMg10Bi2 cuboctahedra that share corners with four equivalent BiLa2Mg10 cuboctahedra, corners with six equivalent LaMg10Bi2 cuboctahedra, corners with eight equivalent MgLa2Mg8Bi2 cuboctahedra, edges with two equivalent BiLa2Mg10 cuboctahedra, edges with four equivalent MgLa2Mg8Bi2 cuboctahedra, faces with two equivalent LaMg10Bi2 cuboctahedra, faces with two equivalent BiLa2Mg10 cuboctahedra, and faces with four equivalent MgLa2Mg8Bi2 cuboctahedra. Both La–Bi bond lengths are 3.19 Å. Bi is bonded to ten Mg and two equivalent La atoms to form distorted BiLa2Mg10 cuboctahedra that share corners with four equivalent LaMg10Bi2 cuboctahedra, corners with six equivalent BiLa2Mg10 cuboctahedra, corners with eight equivalent MgLa2Mg8Bi2 cuboctahedra, edges with two equivalent LaMg10Bi2 cuboctahedra, edges with four equivalent MgLa2Mg8Bi2 cuboctahedra, faces with two equivalent LaMg10Bi2 cuboctahedra, faces with two equivalent BiLa2Mg10 cuboctahedra, and faces with four equivalent MgLa2Mg8Bi2 cuboctahedra.