Tb5Tl3 crystallizes in the tetragonal I4/mcm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent Tl(1) and four equivalent Tl(2) atoms to form distorted corner-sharing TbTl6 octahedra. The corner-sharing octahedral tilt angles range from 0-50°. In the second Tb site, Tb(2) is bonded in a 5-coordinate geometry to two equivalent Tl(1) and three equivalent Tl(2) atoms. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 10-coordinate geometry to two equivalent Tb(1) and eight equivalent Tb(2) atoms. In the second Tl site, Tl(2) is bonded in a 9-coordinate geometry to two equivalent Tb(1), six equivalent Tb(2), and one Tl(2) atom.
Tb5Tl3 crystallizes in the tetragonal I4/mcm space group. There are two inequivalent Tb sites. In the first Tb site, Tb(1) is bonded to two equivalent Tl(1) and four equivalent Tl(2) atoms to form distorted corner-sharing TbTl6 octahedra. The corner-sharing octahedral tilt angles range from 0-50°. Both Tb(1)-Tl(1) bond lengths are 3.64 Å. All Tb(1)-Tl(2) bond lengths are 3.16 Å. In the second Tb site, Tb(2) is bonded in a 5-coordinate geometry to two equivalent Tl(1) and three equivalent Tl(2) atoms. Both Tb(2)-Tl(1) bond lengths are 3.36 Å. There is one shorter (3.21 Å) and two longer (3.26 Å) Tb(2)-Tl(2) bond lengths. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a 10-coordinate geometry to two equivalent Tb(1) and eight equivalent Tb(2) atoms. In the second Tl site, Tl(2) is bonded in a 9-coordinate geometry to two equivalent Tb(1), six equivalent Tb(2), and one Tl(2) atom. The Tl(2)-Tl(2) bond length is 3.06 Å.