MgY crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(3), two equivalent Y(1), two equivalent Y(2), and four equivalent Y(3) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y4Mg8 cuboctahedra, corners with six equivalent Y(2)Y6Mg6 cuboctahedra, edges with three equivalent Y(1)Y4Mg8 cuboctahedra, edges with three equivalent Y(2)Y6Mg6 cuboctahedra, edges with four equivalent Y(3)Y4Mg8 cuboctahedra, edges with eight equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y4Mg8 cuboctahedra, faces with two equivalent Y(2)Y6Mg6 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y4Mg8 cuboctahedra, and faces with six equivalent Mg(3)Y6Mg6 cuboctahedra. In the second Mg site, Mg(2) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Y(1), two equivalent Y(3), and four equivalent Y(2) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(3)Y6Mg6 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(3)Y4Mg8 cuboctahedra, edges with three equivalent Mg(3)Y6Mg6 cuboctahedra, edges with three equivalent Y(3)Y4Mg8 cuboctahedra, edges with four equivalent Y(2)Y6Mg6 cuboctahedra, edges with eight equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y4Mg8 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y6Mg6 cuboctahedra, and faces with six equivalent Y(1)Y4Mg8 cuboctahedra. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Y(3), and four equivalent Y(1) atoms to form distorted MgY6Mg6 cuboctahedra that share corners with six equivalent Mg(3)Y6Mg6 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(3)Y4Mg8 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(3)Y4Mg8 cuboctahedra, edges with four equivalent Y(1)Y4Mg8 cuboctahedra, edges with eight equivalent Y(2)Y6Mg6 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y4Mg8 cuboctahedra, faces with two equivalent Y(2)Y6Mg6 cuboctahedra, faces with four equivalent Mg(3)Y6Mg6 cuboctahedra, faces with four equivalent Y(1)Y4Mg8 cuboctahedra, and faces with six equivalent Mg(1)Y8Mg4 cuboctahedra. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), two equivalent Y(1), and two equivalent Y(2) atoms to form distorted YY4Mg8 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y4Mg8 cuboctahedra, corners with six equivalent Y(2)Y6Mg6 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(2)Y6Mg6 cuboctahedra, edges with four equivalent Mg(3)Y6Mg6 cuboctahedra, edges with eight equivalent Y(3)Y4Mg8 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y4Mg8 cuboctahedra, faces with two equivalent Y(2)Y6Mg6 cuboctahedra, faces with four equivalent Mg(3)Y6Mg6 cuboctahedra, faces with four equivalent Y(1)Y4Mg8 cuboctahedra, and faces with six equivalent Mg(2)Y8Mg4 cuboctahedra. In the second Y site, Y(2) is bonded to two equivalent Mg(1), four equivalent Mg(2), two equivalent Y(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY6Mg6 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y4Mg8 cuboctahedra, corners with six equivalent Y(2)Y6Mg6 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y4Mg8 cuboctahedra, edges with four equivalent Mg(2)Y8Mg4 cuboctahedra, edges with eight equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y4Mg8 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y6Mg6 cuboctahedra, and faces with six equivalent Y(3)Y4Mg8 cuboctahedra. In the third Y site, Y(3) is bonded to two equivalent Mg(2), two equivalent Mg(3), four equivalent Mg(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY4Mg8 cuboctahedra that share corners with six equivalent Mg(3)Y6Mg6 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(3)Y4Mg8 cuboctahedra, edges with three equivalent Mg(3)Y6Mg6 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with four equivalent Mg(1)Y8Mg4 cuboctahedra, edges with eight equivalent Y(1)Y4Mg8 cuboctahedra, faces with two equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y4Mg8 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y4Mg8 cuboctahedra, and faces with six equivalent Y(2)Y6Mg6 cuboctahedra.
MgY crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(3), two equivalent Y(1), two equivalent Y(2), and four equivalent Y(3) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y4Mg8 cuboctahedra, corners with six equivalent Y(2)Y6Mg6 cuboctahedra, edges with three equivalent Y(1)Y4Mg8 cuboctahedra, edges with three equivalent Y(2)Y6Mg6 cuboctahedra, edges with four equivalent Y(3)Y4Mg8 cuboctahedra, edges with eight equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y4Mg8 cuboctahedra, faces with two equivalent Y(2)Y6Mg6 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y4Mg8 cuboctahedra, and faces with six equivalent Mg(3)Y6Mg6 cuboctahedra. Both Mg(1)-Mg(1) bond lengths are 3.47 Å. Both Mg(1)-Mg(3) bond lengths are 3.43 Å. Both Mg(1)-Y(1) bond lengths are 3.27 Å. Both Mg(1)-Y(2) bond lengths are 3.39 Å. All Mg(1)-Y(3) bond lengths are 3.34 Å. In the second Mg site, Mg(2) is bonded to two equivalent Mg(2), two equivalent Mg(3), two equivalent Y(1), two equivalent Y(3), and four equivalent Y(2) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with six equivalent Mg(3)Y6Mg6 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(3)Y4Mg8 cuboctahedra, edges with three equivalent Mg(3)Y6Mg6 cuboctahedra, edges with three equivalent Y(3)Y4Mg8 cuboctahedra, edges with four equivalent Y(2)Y6Mg6 cuboctahedra, edges with eight equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y4Mg8 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y6Mg6 cuboctahedra, and faces with six equivalent Y(1)Y4Mg8 cuboctahedra. Both Mg(2)-Mg(2) bond lengths are 3.47 Å. Both Mg(2)-Mg(3) bond lengths are 3.30 Å. Both Mg(2)-Y(1) bond lengths are 3.45 Å. Both Mg(2)-Y(3) bond lengths are 3.60 Å. All Mg(2)-Y(2) bond lengths are 3.40 Å. In the third Mg site, Mg(3) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Y(3), and four equivalent Y(1) atoms to form distorted MgY6Mg6 cuboctahedra that share corners with six equivalent Mg(3)Y6Mg6 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(3)Y4Mg8 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with three equivalent Y(3)Y4Mg8 cuboctahedra, edges with four equivalent Y(1)Y4Mg8 cuboctahedra, edges with eight equivalent Y(2)Y6Mg6 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y4Mg8 cuboctahedra, faces with two equivalent Y(2)Y6Mg6 cuboctahedra, faces with four equivalent Mg(3)Y6Mg6 cuboctahedra, faces with four equivalent Y(1)Y4Mg8 cuboctahedra, and faces with six equivalent Mg(1)Y8Mg4 cuboctahedra. Both Mg(3)-Mg(3) bond lengths are 3.47 Å. Both Mg(3)-Y(3) bond lengths are 3.31 Å. All Mg(3)-Y(1) bond lengths are 3.33 Å. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), four equivalent Mg(3), two equivalent Y(1), and two equivalent Y(2) atoms to form distorted YY4Mg8 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y4Mg8 cuboctahedra, corners with six equivalent Y(2)Y6Mg6 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(2)Y6Mg6 cuboctahedra, edges with four equivalent Mg(3)Y6Mg6 cuboctahedra, edges with eight equivalent Y(3)Y4Mg8 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(3)Y4Mg8 cuboctahedra, faces with two equivalent Y(2)Y6Mg6 cuboctahedra, faces with four equivalent Mg(3)Y6Mg6 cuboctahedra, faces with four equivalent Y(1)Y4Mg8 cuboctahedra, and faces with six equivalent Mg(2)Y8Mg4 cuboctahedra. Both Y(1)-Y(1) bond lengths are 3.47 Å. Both Y(1)-Y(2) bond lengths are 3.54 Å. In the second Y site, Y(2) is bonded to two equivalent Mg(1), four equivalent Mg(2), two equivalent Y(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY6Mg6 cuboctahedra that share corners with six equivalent Mg(1)Y8Mg4 cuboctahedra, corners with six equivalent Y(1)Y4Mg8 cuboctahedra, corners with six equivalent Y(2)Y6Mg6 cuboctahedra, edges with three equivalent Mg(1)Y8Mg4 cuboctahedra, edges with three equivalent Y(1)Y4Mg8 cuboctahedra, edges with four equivalent Mg(2)Y8Mg4 cuboctahedra, edges with eight equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(1)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y4Mg8 cuboctahedra, faces with four equivalent Mg(2)Y8Mg4 cuboctahedra, faces with four equivalent Y(2)Y6Mg6 cuboctahedra, and faces with six equivalent Y(3)Y4Mg8 cuboctahedra. Both Y(2)-Y(2) bond lengths are 3.47 Å. Both Y(2)-Y(3) bond lengths are 3.49 Å. In the third Y site, Y(3) is bonded to two equivalent Mg(2), two equivalent Mg(3), four equivalent Mg(1), two equivalent Y(2), and two equivalent Y(3) atoms to form YY4Mg8 cuboctahedra that share corners with six equivalent Mg(3)Y6Mg6 cuboctahedra, corners with six equivalent Mg(2)Y8Mg4 cuboctahedra, corners with six equivalent Y(3)Y4Mg8 cuboctahedra, edges with three equivalent Mg(3)Y6Mg6 cuboctahedra, edges with three equivalent Mg(2)Y8Mg4 cuboctahedra, edges with four equivalent Mg(1)Y8Mg4 cuboctahedra, edges with eight equivalent Y(1)Y4Mg8 cuboctahedra, faces with two equivalent Mg(3)Y6Mg6 cuboctahedra, faces with two equivalent Mg(2)Y8Mg4 cuboctahedra, faces with two equivalent Y(1)Y4Mg8 cuboctahedra, faces with four equivalent Mg(1)Y8Mg4 cuboctahedra, faces with four equivalent Y(3)Y4Mg8 cuboctahedra, and faces with six equivalent Y(2)Y6Mg6 cuboctahedra. Both Y(3)-Y(3) bond lengths are 3.47 Å.