DOE OSTI2020
Mg6YGa is beta-derived structured and 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 Y, and two equivalent Ga atoms to form distorted MgY2Mg8Ga2 cuboctahedra that share corners with four equivalent YMg10Ga2 cuboctahedra, corners with fourteen MgY2Mg8Ga2 cuboctahedra, edges with two equivalent YMg10Ga2 cuboctahedra, edges with four equivalent GaY2Mg10 cuboctahedra, edges with twelve MgY2Mg8Ga2 cuboctahedra, faces with two equivalent YMg10Ga2 cuboctahedra, faces with two equivalent GaY2Mg10 cuboctahedra, and faces with sixteen MgY2Mg8Ga2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.10–3.38 Å. There are one shorter (3.20 Å) and one longer (3.37 Å) Mg–Y bond lengths. Both Mg–Ga bond lengths are 3.13 Å. In the second Mg site, Mg is bonded to ten Mg and two equivalent Y atoms to form MgY2Mg10 cuboctahedra that share corners with four equivalent YMg10Ga2 cuboctahedra, corners with fourteen MgY2Mg8Ga2 cuboctahedra, edges with two equivalent YMg10Ga2 cuboctahedra, edges with sixteen MgY2Mg8Ga2 cuboctahedra, faces with two equivalent YMg10Ga2 cuboctahedra, faces with six equivalent GaY2Mg10 cuboctahedra, and faces with twelve MgY2Mg8Ga2 cuboctahedra. There are four shorter (3.11 Å) and two longer (3.14 Å) Mg–Mg bond lengths. Both Mg–Y bond lengths are 3.30 Å. In the third Mg site, Mg is bonded to eight Mg, two equivalent Y, and two equivalent Ga atoms to form distorted MgY2Mg8Ga2 cuboctahedra that share corners with four equivalent GaY2Mg10 cuboctahedra, corners with fourteen MgY2Mg8Ga2 cuboctahedra, edges with two equivalent GaY2Mg10 cuboctahedra, edges with four equivalent YMg10Ga2 cuboctahedra, edges with twelve MgY2Mg8Ga2 cuboctahedra, faces with two equivalent YMg10Ga2 cuboctahedra, faces with two equivalent GaY2Mg10 cuboctahedra, and faces with sixteen MgY2Mg8Ga2 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.19–3.40 Å. Both Mg–Y bond lengths are 3.20 Å. There are one shorter (3.26 Å) and one longer (3.30 Å) Mg–Ga bond lengths. In the fourth Mg site, Mg is bonded to ten Mg and two equivalent Ga atoms to form distorted MgMg10Ga2 cuboctahedra that share corners with four equivalent GaY2Mg10 cuboctahedra, corners with fourteen MgY2Mg8Ga2 cuboctahedra, edges with two equivalent GaY2Mg10 cuboctahedra, edges with sixteen MgY2Mg8Ga2 cuboctahedra, faces with two equivalent GaY2Mg10 cuboctahedra, faces with six equivalent YMg10Ga2 cuboctahedra, and faces with twelve MgY2Mg8Ga2 cuboctahedra. Both Mg–Ga bond lengths are 3.29 Å. Y is bonded to ten Mg and two equivalent Ga atoms to form distorted YMg10Ga2 cuboctahedra that share corners with six equivalent YMg10Ga2 cuboctahedra, corners with twelve MgY2Mg8Ga2 cuboctahedra, edges with four equivalent GaY2Mg10 cuboctahedra, edges with fourteen MgY2Mg8Ga2 cuboctahedra, faces with two equivalent YMg10Ga2 cuboctahedra, faces with two equivalent GaY2Mg10 cuboctahedra, and faces with sixteen MgY2Mg8Ga2 cuboctahedra. Both Y–Ga bond lengths are 3.05 Å. Ga is bonded to ten Mg and two equivalent Y atoms to form distorted GaY2Mg10 cuboctahedra that share corners with six equivalent GaY2Mg10 cuboctahedra, corners with twelve MgY2Mg8Ga2 cuboctahedra, edges with four equivalent YMg10Ga2 cuboctahedra, edges with fourteen MgY2Mg8Ga2 cuboctahedra, faces with two equivalent YMg10Ga2 cuboctahedra, faces with two equivalent GaY2Mg10 cuboctahedra, and faces with sixteen MgY2Mg8Ga2 cuboctahedra.