Er2AlSi crystallizes in the orthorhombic Pmc2_1 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to three equivalent Al(1) and four equivalent Si(1) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to four equivalent Al(1) and three equivalent Si(1) atoms. Al(1) is bonded in a 9-coordinate geometry to three equivalent Er(1), four equivalent Er(2), and two equivalent Si(1) atoms. Si(1) is bonded in a 9-coordinate geometry to three equivalent Er(2), four equivalent Er(1), and two equivalent Al(1) atoms.
Er2AlSi crystallizes in the orthorhombic Pmc2_1 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to three equivalent Al(1) and four equivalent Si(1) atoms. There are a spread of Er(1)-Al(1) bond distances ranging from 3.06-3.18 Å. There are two shorter (2.99 Å) and two longer (3.01 Å) Er(1)-Si(1) bond lengths. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to four equivalent Al(1) and three equivalent Si(1) atoms. There are two shorter (3.01 Å) and two longer (3.03 Å) Er(2)-Al(1) bond lengths. There are a spread of Er(2)-Si(1) bond distances ranging from 3.00-3.19 Å. Al(1) is bonded in a 9-coordinate geometry to three equivalent Er(1), four equivalent Er(2), and two equivalent Si(1) atoms. Both Al(1)-Si(1) bond lengths are 2.54 Å. Si(1) is bonded in a 9-coordinate geometry to three equivalent Er(2), four equivalent Er(1), and two equivalent Al(1) atoms.