Y12Al7Si crystallizes in the tetragonal I4/mcm space group. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded in a 4-coordinate geometry to two equivalent Al(1) and two equivalent Al(3) atoms. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one Al(1), one Al(2), three equivalent Al(3), and one Si(1) atom. In the third Y site, Y(3) is bonded in a 5-coordinate geometry to two equivalent Al(3) and three equivalent Al(1) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to two equivalent Y(1), three equivalent Y(3), and four equivalent Y(2) atoms. In the second Al site, Al(2) is bonded in a body-centered cubic geometry to eight equivalent Y(2) atoms. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to one Y(1), one Y(3), six equivalent Y(2), and one Al(3) atom. Si(1) is bonded in a 8-coordinate geometry to eight equivalent Y(2) atoms.
Y12Al7Si crystallizes in the tetragonal I4/mcm space group. There are three inequivalent Y sites. In the first Y site, Y(1) is bonded in a 4-coordinate geometry to two equivalent Al(1) and two equivalent Al(3) atoms. Both Y(1)-Al(1) bond lengths are 2.98 Å. Both Y(1)-Al(3) bond lengths are 3.09 Å. In the second Y site, Y(2) is bonded in a 6-coordinate geometry to one Al(1), one Al(2), three equivalent Al(3), and one Si(1) atom. The Y(2)-Al(1) bond length is 3.04 Å. The Y(2)-Al(2) bond length is 3.23 Å. There are a spread of Y(2)-Al(3) bond distances ranging from 3.12-3.34 Å. The Y(2)-Si(1) bond length is 3.01 Å. In the third Y site, Y(3) is bonded in a 5-coordinate geometry to two equivalent Al(3) and three equivalent Al(1) atoms. Both Y(3)-Al(3) bond lengths are 3.09 Å. There are two shorter (3.45 Å) and one longer (3.50 Å) Y(3)-Al(1) bond length. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to two equivalent Y(1), three equivalent Y(3), and four equivalent Y(2) atoms. In the second Al site, Al(2) is bonded in a body-centered cubic geometry to eight equivalent Y(2) atoms. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to one Y(1), one Y(3), six equivalent Y(2), and one Al(3) atom. The Al(3)-Al(3) bond length is 2.76 Å. Si(1) is bonded in a 8-coordinate geometry to eight equivalent Y(2) atoms.