MgY is beta-derived structured and crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(2); three equivalent Mg(1); three equivalent Y(1); and four Y(2,2) atoms. In the second Mg site, Mg(2) is bonded to four equivalent Mg(1); two equivalent Y(1); and six Y(2,2) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with eighteen Y(2,2)Y5Mg7 cuboctahedra; edges with four equivalent Y(1)Y4Mg8 cuboctahedra; edges with six equivalent Mg(2)Y8Mg4 cuboctahedra; faces with two equivalent Mg(2)Y8Mg4 cuboctahedra; faces with four equivalent Y(1)Y4Mg8 cuboctahedra; and faces with six Y(2,2)Y5Mg7 cuboctahedra. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(2), six equivalent Mg(1), and four equivalent Y(2) atoms to form distorted YY4Mg8 cuboctahedra that share edges with four equivalent Mg(2)Y8Mg4 cuboctahedra; edges with six equivalent Y(1)Y4Mg8 cuboctahedra; edges with eight Y(2,2)Y5Mg7 cuboctahedra; faces with two equivalent Y(1)Y4Mg8 cuboctahedra; faces with four equivalent Mg(2)Y8Mg4 cuboctahedra; and faces with eight Y(2,2)Y5Mg7 cuboctahedra. In the second Y site, Y(2) is bonded to three equivalent Mg(2); four equivalent Mg(1); two equivalent Y(1); and three Y(2,2) atoms to form distorted YY5Mg7 cuboctahedra that share corners with nine equivalent Mg(2)Y8Mg4 cuboctahedra; corners with nine Y(2,2)Y5Mg7 cuboctahedra; edges with four equivalent Y(1)Y4Mg8 cuboctahedra; edges with six equivalent Y(2)Y5Mg7 cuboctahedra; faces with three equivalent Mg(2)Y8Mg4 cuboctahedra; faces with four equivalent Y(1)Y4Mg8 cuboctahedra; and faces with five Y(2,2)Y5Mg7 cuboctahedra. In the third Y site, Y(2) is bonded to three equivalent Mg(2), four equivalent Mg(1), two equivalent Y(1), and three equivalent Y(2) atoms to form distorted YY5Mg7 cuboctahedra that share corners with nine equivalent Mg(2)Y8Mg4 cuboctahedra; corners with nine equivalent Y(2)Y5Mg7 cuboctahedra; edges with four equivalent Y(1)Y4Mg8 cuboctahedra; edges with six Y(2,2)Y5Mg7 cuboctahedra; faces with three equivalent Mg(2)Y8Mg4 cuboctahedra; faces with four equivalent Y(1)Y4Mg8 cuboctahedra; and faces with five Y(2,2)Y5Mg7 cuboctahedra.
MgY is beta-derived structured and crystallizes in the orthorhombic Amm2 space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 12-coordinate geometry to two equivalent Mg(2); three equivalent Mg(1); three equivalent Y(1); and four Y(2,2) atoms. Both Mg(1)-Mg(2) bond lengths are 3.37 Å. There is one shorter (3.31 Å) and two longer (3.51 Å) Mg(1)-Mg(1) bond lengths. There are a spread of Mg(1)-Y(1) bond distances ranging from 3.30-3.63 Å. There are two shorter (3.26 Å) and two longer (3.40 Å) Mg(1)-Y(2,2) bond lengths. In the second Mg site, Mg(2) is bonded to four equivalent Mg(1); two equivalent Y(1); and six Y(2,2) atoms to form distorted MgY8Mg4 cuboctahedra that share corners with eighteen Y(2,2)Y5Mg7 cuboctahedra; edges with four equivalent Y(1)Y4Mg8 cuboctahedra; edges with six equivalent Mg(2)Y8Mg4 cuboctahedra; faces with two equivalent Mg(2)Y8Mg4 cuboctahedra; faces with four equivalent Y(1)Y4Mg8 cuboctahedra; and faces with six Y(2,2)Y5Mg7 cuboctahedra. Both Mg(2)-Y(1) bond lengths are 3.25 Å. There are a spread of Mg(2)-Y(2,2) bond distances ranging from 3.25-3.69 Å. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded to two equivalent Mg(2), six equivalent Mg(1), and four equivalent Y(2) atoms to form distorted YY4Mg8 cuboctahedra that share edges with four equivalent Mg(2)Y8Mg4 cuboctahedra; edges with six equivalent Y(1)Y4Mg8 cuboctahedra; edges with eight Y(2,2)Y5Mg7 cuboctahedra; faces with two equivalent Y(1)Y4Mg8 cuboctahedra; faces with four equivalent Mg(2)Y8Mg4 cuboctahedra; and faces with eight Y(2,2)Y5Mg7 cuboctahedra. All Y(1)-Y(2) bond lengths are 3.58 Å. In the second Y site, Y(2) is bonded to three equivalent Mg(2); four equivalent Mg(1); two equivalent Y(1); and three Y(2,2) atoms to form distorted YY5Mg7 cuboctahedra that share corners with nine equivalent Mg(2)Y8Mg4 cuboctahedra; corners with nine Y(2,2)Y5Mg7 cuboctahedra; edges with four equivalent Y(1)Y4Mg8 cuboctahedra; edges with six equivalent Y(2)Y5Mg7 cuboctahedra; faces with three equivalent Mg(2)Y8Mg4 cuboctahedra; faces with four equivalent Y(1)Y4Mg8 cuboctahedra; and faces with five Y(2,2)Y5Mg7 cuboctahedra. There are two shorter (3.36 Å) and one longer (3.63 Å) Y(2)-Y(2,2) bond length. In the third Y site, Y(2) is bonded to three equivalent Mg(2), four equivalent Mg(1), two equivalent Y(1), and three equivalent Y(2) atoms to form distorted YY5Mg7 cuboctahedra that share corners with nine equivalent Mg(2)Y8Mg4 cuboctahedra; corners with nine equivalent Y(2)Y5Mg7 cuboctahedra; edges with four equivalent Y(1)Y4Mg8 cuboctahedra; edges with six Y(2,2)Y5Mg7 cuboctahedra; faces with three equivalent Mg(2)Y8Mg4 cuboctahedra; faces with four equivalent Y(1)Y4Mg8 cuboctahedra; and faces with five Y(2,2)Y5Mg7 cuboctahedra. Both Y(2)-Y(1) bond lengths are 3.58 Å.