Al2Er3 crystallizes in the tetragonal P4_2/mnm space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a distorted square co-planar geometry to four equivalent Al(1) atoms. In the second Er site, Er(3) is bonded in a 6-coordinate geometry to six equivalent Al(1) atoms. In the third Er site, Er(2) is bonded in a 6-coordinate geometry to six equivalent Al(1) atoms. Al(1) is bonded in a 10-coordinate geometry to two equivalent Er(1), three equivalent Er(2), three equivalent Er(3), and two equivalent Al(1) atoms.
Al2Er3 crystallizes in the tetragonal P4_2/mnm space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a distorted square co-planar geometry to four equivalent Al(1) atoms. All Er(1)-Al(1) bond lengths are 3.26 Å. In the second Er site, Er(3) is bonded in a 6-coordinate geometry to six equivalent Al(1) atoms. There are four shorter (3.07 Å) and two longer (3.08 Å) Er(3)-Al(1) bond lengths. In the third Er site, Er(2) is bonded in a 6-coordinate geometry to six equivalent Al(1) atoms. There are two shorter (3.03 Å) and four longer (3.18 Å) Er(2)-Al(1) bond lengths. Al(1) is bonded in a 10-coordinate geometry to two equivalent Er(1), three equivalent Er(2), three equivalent Er(3), and two equivalent Al(1) atoms. There is one shorter (2.72 Å) and one longer (2.98 Å) Al(1)-Al(1) bond length.