DOI: 10.17188/1721266
title: Materials Data on MgAlCu by Materials Project

description: MgCuAl crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are seven inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, six Cu, and six equivalent Al atoms. There are three shorter (3.19 Å) and one longer (3.26 Å) Mg–Mg bond lengths. There are three shorter (2.84 Å) and three longer (3.05 Å) Mg–Cu bond lengths. All Mg–Al bond lengths are 3.13 Å. In the second Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, nine Cu, and three equivalent Al atoms. The Mg–Mg bond length is 2.86 Å. There are six shorter (2.99 Å) and three longer (3.10 Å) Mg–Cu bond lengths. All Mg–Al bond lengths are 3.07 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, nine Cu, and three equivalent Al atoms. There are one shorter (2.86 Å) and three longer (3.19 Å) Mg–Mg bond lengths. There are six shorter (2.99 Å) and three longer (3.10 Å) Mg–Cu bond lengths. All Mg–Al bond lengths are 3.07 Å. In the fourth Mg site, Mg is bonded in a 12-coordinate geometry to one Mg, three equivalent Cu, and nine equivalent Al atoms. All Mg–Cu bond lengths are 3.08 Å. There are three shorter (3.04 Å) and six longer (3.06 Å) Mg–Al bond lengths. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, nine Cu, and three equivalent Al atoms. There are one shorter (2.86 Å) and three longer (3.19 Å) Mg–Mg bond lengths. There are six shorter (2.99 Å) and three longer (3.10 Å) Mg–Cu bond lengths. All Mg–Al bond lengths are 3.07 Å. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, nine Cu, and three equivalent Al atoms. All Mg–Mg bond lengths are 3.19 Å. There are six shorter (2.99 Å) and three longer (3.10 Å) Mg–Cu bond lengths. All Mg–Al bond lengths are 3.07 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to four Mg, nine Cu, and three equivalent Al atoms. All Mg–Mg bond lengths are 3.19 Å. There are six shorter (2.99 Å) and three longer (3.10 Å) Mg–Cu bond lengths. All Mg–Al bond lengths are 3.07 Å. There are three inequivalent Cu sites. In the first Cu site, Cu is bonded to six Mg, three equivalent Cu, and three equivalent Al atoms to form CuMg6Al3Cu3 cuboctahedra that share corners with six equivalent AlMg6Al4Cu2 cuboctahedra, corners with nine CuMg6Al3Cu3 cuboctahedra, edges with six equivalent CuMg6Al3Cu3 cuboctahedra, faces with nine equivalent AlMg6Al4Cu2 cuboctahedra, and faces with ten CuMg6Cu6 cuboctahedra. All Cu–Cu bond lengths are 2.55 Å. All Cu–Al bond lengths are 2.55 Å. In the second Cu site, Cu is bonded to six Mg and six Cu atoms to form CuMg6Cu6 cuboctahedra that share corners with eight CuMg6Al3Cu3 cuboctahedra, corners with ten equivalent AlMg6Al4Cu2 cuboctahedra, edges with two equivalent CuMg6Cu6 cuboctahedra, edges with four equivalent AlMg6Al4Cu2 cuboctahedra, faces with four equivalent AlMg6Al4Cu2 cuboctahedra, and faces with fourteen CuMg6Al3Cu3 cuboctahedra. All Cu–Cu bond lengths are 2.63 Å. In the third Cu site, Cu is bonded to six equivalent Mg and six equivalent Al atoms to form CuMg6Al6 cuboctahedra that share corners with twelve equivalent AlMg6Al4Cu2 cuboctahedra, edges with six equivalent CuMg6Al6 cuboctahedra, faces with two equivalent CuMg6Al3Cu3 cuboctahedra, and faces with eighteen equivalent AlMg6Al4Cu2 cuboctahedra. All Cu–Al bond lengths are 2.60 Å. Al is bonded to six Mg, two Cu, and four equivalent Al atoms to form distorted AlMg6Al4Cu2 cuboctahedra that share corners with nine CuMg6Al3Cu3 cuboctahedra, corners with nine equivalent AlMg6Al4Cu2 cuboctahedra, edges with two equivalent CuMg6Cu6 cuboctahedra, edges with four equivalent AlMg6Al4Cu2 cuboctahedra, faces with eight CuMg6Al3Cu3 cuboctahedra, and faces with ten equivalent AlMg6Al4Cu2 cuboctahedra. There are two shorter (2.61 Å) and two longer (2.64 Å) Al–Al bond lengths.