Mg5Y5Al12(Fe2Si3)2 crystallizes in the tetragonal P4/mmm 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 Fe(1), two equivalent Al(2), four equivalent Al(1), and four equivalent Si(1) atoms. In the second Mg site, Mg(2) is bonded in a square co-planar geometry to four equivalent Al(2) atoms. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 9-coordinate geometry to four equivalent Al(1), four equivalent Al(2), and one Si(2) atom. In the second Y site, Y(2) is bonded in a distorted body-centered cubic geometry to eight equivalent Si(1) atoms. Fe(1) is bonded in a 9-coordinate geometry to two equivalent Mg(1), four equivalent Al(1), one Si(2), and two equivalent Si(1) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Y(1), two equivalent Fe(1), one Al(2), two equivalent Al(1), one Si(1), and two equivalent Si(2) atoms. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(1), four equivalent Y(1), and two equivalent Al(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to four equivalent Mg(1), two equivalent Y(2), two equivalent Fe(1), and two equivalent Al(1) atoms. In the second Si site, Si(2) is bonded to two equivalent Y(1), two equivalent Fe(1), and eight equivalent Al(1) atoms to form face-sharing SiY2Al8Fe2 cuboctahedra.
Mg5Y5Al12(Fe2Si3)2 crystallizes in the tetragonal P4/mmm 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 Fe(1), two equivalent Al(2), four equivalent Al(1), and four equivalent Si(1) atoms. Both Mg(1)-Fe(1) bond lengths are 2.71 Å. Both Mg(1)-Al(2) bond lengths are 2.96 Å. All Mg(1)-Al(1) bond lengths are 3.05 Å. All Mg(1)-Si(1) bond lengths are 3.13 Å. In the second Mg site, Mg(2) is bonded in a square co-planar geometry to four equivalent Al(2) atoms. All Mg(2)-Al(2) bond lengths are 2.84 Å. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 9-coordinate geometry to four equivalent Al(1), four equivalent Al(2), and one Si(2) atom. All Y(1)-Al(1) bond lengths are 3.01 Å. All Y(1)-Al(2) bond lengths are 2.99 Å. The Y(1)-Si(2) bond length is 3.00 Å. In the second Y site, Y(2) is bonded in a distorted body-centered cubic geometry to eight equivalent Si(1) atoms. All Y(2)-Si(1) bond lengths are 3.01 Å. Fe(1) is bonded in a 9-coordinate geometry to two equivalent Mg(1), four equivalent Al(1), one Si(2), and two equivalent Si(1) atoms. All Fe(1)-Al(1) bond lengths are 2.53 Å. The Fe(1)-Si(2) bond length is 2.31 Å. Both Fe(1)-Si(1) bond lengths are 2.44 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded in a 12-coordinate geometry to two equivalent Mg(1), two equivalent Y(1), two equivalent Fe(1), one Al(2), two equivalent Al(1), one Si(1), and two equivalent Si(2) atoms. The Al(1)-Al(2) bond length is 2.66 Å. There is one shorter (2.67 Å) and one longer (3.03 Å) Al(1)-Al(1) bond length. The Al(1)-Si(1) bond length is 2.56 Å. Both Al(1)-Si(2) bond lengths are 2.84 Å. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to one Mg(2), two equivalent Mg(1), four equivalent Y(1), and two equivalent Al(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 10-coordinate geometry to four equivalent Mg(1), two equivalent Y(2), two equivalent Fe(1), and two equivalent Al(1) atoms. In the second Si site, Si(2) is bonded to two equivalent Y(1), two equivalent Fe(1), and eight equivalent Al(1) atoms to form face-sharing SiY2Al8Fe2 cuboctahedra.