Er5Bi3 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded in a 5-coordinate geometry to two equivalent Bi(1) and three equivalent Bi(2) atoms. In the second Er site, Er(2) is bonded in a 6-coordinate geometry to two equivalent Bi(1) and four equivalent Bi(2) atoms. In the third Er site, Er(3) is bonded to one Bi(1) and four equivalent Bi(2) atoms to form distorted edge-sharing ErBi5 square pyramids. In the fourth Er site, Er(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 Er(3), one Er(4), two equivalent Er(2), and four equivalent Er(1) atoms. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to two equivalent Er(2), two equivalent Er(3), two equivalent Er(4), and three equivalent Er(1) atoms.
Er5Bi3 crystallizes in the orthorhombic Pnma space group. There are four inequivalent Er sites. In the first Er site, Er(1) is bonded in a 5-coordinate geometry to two equivalent Bi(1) and three equivalent Bi(2) atoms. There is one shorter (3.05 Å) and one longer (3.15 Å) Er(1)-Bi(1) bond length. There are a spread of Er(1)-Bi(2) bond distances ranging from 3.30-3.55 Å. In the second Er site, Er(2) is bonded in a 6-coordinate geometry to two equivalent Bi(1) and four equivalent Bi(2) atoms. There is one shorter (3.08 Å) and one longer (3.46 Å) Er(2)-Bi(1) bond length. There are two shorter (3.19 Å) and two longer (3.31 Å) Er(2)-Bi(2) bond lengths. In the third Er site, Er(3) is bonded to one Bi(1) and four equivalent Bi(2) atoms to form distorted edge-sharing ErBi5 square pyramids. The Er(3)-Bi(1) bond length is 3.13 Å. There are two shorter (3.17 Å) and two longer (3.19 Å) Er(3)-Bi(2) bond lengths. In the fourth Er site, Er(4) is bonded in a 5-coordinate geometry to one Bi(1) and four equivalent Bi(2) atoms. The Er(4)-Bi(1) bond length is 3.04 Å. There are two shorter (3.24 Å) and two longer (3.32 Å) Er(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 Er(3), one Er(4), two equivalent Er(2), and four equivalent Er(1) atoms. In the second Bi site, Bi(2) is bonded in a 9-coordinate geometry to two equivalent Er(2), two equivalent Er(3), two equivalent Er(4), and three equivalent Er(1) atoms.