Tb5Bi3 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 5-coordinate geometry to two equivalent Bi(1) and three equivalent Bi(2) atoms. In the second Tb site, Tb(2) is bonded in a 6-coordinate geometry to two equivalent Bi(1) and four equivalent Bi(2) atoms. In the third Tb site, Tb(3) is bonded to one Bi(1) and four equivalent Bi(2) atoms to form distorted edge-sharing TbBi5 square pyramids. In the fourth Tb site, Tb(4) is bonded in a 5-coordinate geometry to one Bi(1) and four equivalent Bi(2) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 8-coordinate geometry to one Tb(3), one Tb(4), two equivalent Tb(2), and four equivalent Tb(1) atoms. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to two equivalent Tb(2), two equivalent Tb(3), two equivalent Tb(4), and three equivalent Tb(1) atoms.
Tb5Bi3 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 5-coordinate geometry to two equivalent Bi(1) and three equivalent Bi(2) atoms. There is one shorter (3.09 Å) and one longer (3.20 Å) Tb(1)-Bi(1) bond length. There are a spread of Tb(1)-Bi(2) bond distances ranging from 3.36-3.60 Å. In the second Tb site, Tb(2) is bonded in a 6-coordinate geometry to two equivalent Bi(1) and four equivalent Bi(2) atoms. There is one shorter (3.13 Å) and one longer (3.55 Å) Tb(2)-Bi(1) bond length. There are two shorter (3.24 Å) and two longer (3.36 Å) Tb(2)-Bi(2) bond lengths. In the third Tb site, Tb(3) is bonded to one Bi(1) and four equivalent Bi(2) atoms to form distorted edge-sharing TbBi5 square pyramids. The Tb(3)-Bi(1) bond length is 3.17 Å. There are two shorter (3.22 Å) and two longer (3.24 Å) Tb(3)-Bi(2) bond lengths. In the fourth Tb site, Tb(4) is bonded in a 5-coordinate geometry to one Bi(1) and four equivalent Bi(2) atoms. The Tb(4)-Bi(1) bond length is 3.07 Å. There are two shorter (3.29 Å) and two longer (3.37 Å) Tb(4)-Bi(2) bond lengths. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 8-coordinate geometry to one Tb(3), one Tb(4), two equivalent Tb(2), and four equivalent Tb(1) atoms. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to two equivalent Tb(2), two equivalent Tb(3), two equivalent Tb(4), and three equivalent Tb(1) atoms.