Materials Data on Sr2Mg3Al by Materials Project
Sr2Mg3Al crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded in a 12-coordinate geometry to nine Mg and three equivalent Al atoms. There are six shorter (3.69 Å) and three longer (3.70 Å) Sr–Mg bond lengths. All Sr–Al bond lengths are 3.64 Å. In the second Sr site, Sr is bonded in a 12-coordinate geometry to nine Mg and three equivalent Al atoms. There are three shorter (3.67 Å) and six longer (3.71 Å) Sr–Mg bond lengths. All Sr–Al bond lengths are 3.67 Å. There are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six Sr, four equivalent Mg, and two equivalent Al atoms to form distorted MgSr6Mg4Al2 cuboctahedra that share corners with four equivalent AlSr6Mg6 cuboctahedra, corners with fourteen MgSr6Mg4Al2 cuboctahedra, edges with six MgSr6Mg4Al2 cuboctahedra, faces with six equivalent AlSr6Mg6 cuboctahedra, and faces with twelve MgSr6Mg4Al2 cuboctahedra. There are two shorter (3.10 Å) and two longer (3.14 Å) Mg–Mg bond lengths. Both Mg–Al bond lengths are 3.06 Å. In the second Mg site, Mg is bonded to six Sr, four equivalent Mg, and two equivalent Al atoms to form MgSr6Mg4Al2 cuboctahedra that share corners with four equivalent AlSr6Mg6 cuboctahedra, corners with fourteen MgSr6Mg4Al2 cuboctahedra, edges with six MgSr6Mg4Al2 cuboctahedra, faces with six equivalent AlSr6Mg6 cuboctahedra, and faces with twelve MgSr6Mg4Al2 cuboctahedra. All Mg–Mg bond lengths are 3.12 Å. Both Mg–Al bond lengths are 3.27 Å. Al is bonded to six Sr and six Mg atoms to form AlSr6Mg6 cuboctahedra that share corners with three equivalent AlSr6Mg6 cuboctahedra, corners with twelve MgSr6Mg4Al2 cuboctahedra, edges with six equivalent AlSr6Mg6 cuboctahedra, a faceface with one AlSr6Mg6 cuboctahedra, and faces with eighteen MgSr6Mg4Al2 cuboctahedra.