Al2Si2Sr3 crystallizes in the orthorhombic Immm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to eight equivalent Al(1) and four equivalent Si(1) atoms to form a mixture of face and edge-sharing SrAl8Si4 cuboctahedra. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to two equivalent Al(1) and five equivalent Si(1) atoms. Al(1) is bonded in a 9-coordinate geometry to two equivalent Sr(2), four equivalent Sr(1), one Al(1), and two equivalent Si(1) atoms. Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), five equivalent Sr(2), and two equivalent Al(1) atoms.
Al2Si2Sr3 crystallizes in the orthorhombic Immm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to eight equivalent Al(1) and four equivalent Si(1) atoms to form a mixture of face and edge-sharing SrAl8Si4 cuboctahedra. All Sr(1)-Al(1) bond lengths are 3.46 Å. All Sr(1)-Si(1) bond lengths are 3.60 Å. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to two equivalent Al(1) and five equivalent Si(1) atoms. Both Sr(2)-Al(1) bond lengths are 3.32 Å. There are four shorter (3.33 Å) and one longer (3.38 Å) Sr(2)-Si(1) bond length. Al(1) is bonded in a 9-coordinate geometry to two equivalent Sr(2), four equivalent Sr(1), one Al(1), and two equivalent Si(1) atoms. The Al(1)-Al(1) bond length is 2.56 Å. Both Al(1)-Si(1) bond lengths are 2.51 Å. Si(1) is bonded in a 9-coordinate geometry to two equivalent Sr(1), five equivalent Sr(2), and two equivalent Al(1) atoms.