DOE OSTI2020
Mg5Tm is Magnesium-derived structured and crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are five inequivalent Mg sites. In the first Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eight equivalent TmTm2Mg10 cuboctahedra, edges with ten MgTm4Mg8 cuboctahedra, faces with two equivalent TmTm2Mg10 cuboctahedra, and faces with eighteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.20–3.27 Å. In the second Mg site, Mg is bonded to eight Mg and four equivalent Tm atoms to form MgTm4Mg8 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with four equivalent TmTm2Mg10 cuboctahedra, edges with fourteen MgMg12 cuboctahedra, faces with four equivalent TmTm2Mg10 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.22–3.34 Å. All Mg–Tm bond lengths are 3.27 Å. In the third Mg site, Mg is bonded to ten Mg and two equivalent Tm atoms to form MgTm2Mg10 cuboctahedra that share corners with eighteen MgMg12 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, faces with six equivalent TmTm2Mg10 cuboctahedra, and faces with fourteen MgMg12 cuboctahedra. There are two shorter (3.22 Å) and four longer (3.27 Å) Mg–Mg bond lengths. Both Mg–Tm bond lengths are 3.33 Å. In the fourth Mg site, Mg is bonded to ten Mg and two equivalent Tm atoms to form MgTm2Mg10 cuboctahedra that share corners with six equivalent TmTm2Mg10 cuboctahedra, corners with twelve MgTm2Mg10 cuboctahedra, edges with three equivalent TmTm2Mg10 cuboctahedra, edges with fifteen MgMg12 cuboctahedra, faces with two equivalent TmTm2Mg10 cuboctahedra, and faces with eighteen MgMg12 cuboctahedra. There are two shorter (3.16 Å) and two longer (3.22 Å) Mg–Mg bond lengths. Both Mg–Tm bond lengths are 3.28 Å. In the fifth Mg site, Mg is bonded to ten Mg and two equivalent Tm atoms to form MgTm2Mg10 cuboctahedra that share corners with six equivalent TmTm2Mg10 cuboctahedra, corners with twelve MgTm2Mg10 cuboctahedra, edges with three equivalent TmTm2Mg10 cuboctahedra, edges with fifteen MgTm4Mg8 cuboctahedra, faces with two equivalent TmTm2Mg10 cuboctahedra, and faces with eighteen MgMg12 cuboctahedra. Both Mg–Mg bond lengths are 3.22 Å. Both Mg–Tm bond lengths are 3.33 Å. Tm is bonded to ten Mg and two equivalent Tm atoms to form TmTm2Mg10 cuboctahedra that share corners with six equivalent TmTm2Mg10 cuboctahedra, corners with twelve MgTm2Mg10 cuboctahedra, edges with eighteen MgMg12 cuboctahedra, faces with four equivalent TmTm2Mg10 cuboctahedra, and faces with sixteen MgMg12 cuboctahedra. Both Tm–Tm bond lengths are 3.22 Å.