Sr8Fe8O23 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(1), one O(5), two equivalent O(3), four equivalent O(2), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with six equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Fe(1)O6 octahedra, faces with four equivalent Fe(2)O6 octahedra, and faces with two equivalent Fe(3)O5 square pyramids. In the second Sr site, Sr(2) is bonded in a distorted q6 geometry to one O(1), two equivalent O(3), four equivalent O(2), and four equivalent O(4) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O5 square pyramids, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the third Fe site, Fe(3) is bonded to one O(5) and four equivalent O(4) atoms to form FeO5 square pyramids that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O5 square pyramid, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 12°. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form a mixture of distorted corner and face-sharing OSr4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner, edge, and face-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Fe(2), and one Fe(3) atom. In the fifth O site, O(5) is bonded to four equivalent Sr(1) and two equivalent Fe(3) atoms to form distorted corner-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°.
Sr8Fe8O23 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(1), one O(5), two equivalent O(3), four equivalent O(2), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with six equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Fe(1)O6 octahedra, faces with four equivalent Fe(2)O6 octahedra, and faces with two equivalent Fe(3)O5 square pyramids. The Sr(1)-O(1) bond length is 2.72 Å. The Sr(1)-O(5) bond length is 2.73 Å. Both Sr(1)-O(3) bond lengths are 2.61 Å. All Sr(1)-O(2) bond lengths are 2.72 Å. All Sr(1)-O(4) bond lengths are 2.86 Å. In the second Sr site, Sr(2) is bonded in a distorted q6 geometry to one O(1), two equivalent O(3), four equivalent O(2), and four equivalent O(4) atoms. The Sr(2)-O(1) bond length is 2.63 Å. Both Sr(2)-O(3) bond lengths are 2.84 Å. All Sr(2)-O(2) bond lengths are 2.67 Å. All Sr(2)-O(4) bond lengths are 2.64 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with four equivalent Fe(2)O6 octahedra, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Both Fe(1)-O(1) bond lengths are 1.92 Å. All Fe(1)-O(2) bond lengths are 1.91 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O5 square pyramids, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. Both Fe(2)-O(2) bond lengths are 1.94 Å. Both Fe(2)-O(3) bond lengths are 1.92 Å. Both Fe(2)-O(4) bond lengths are 2.01 Å. In the third Fe site, Fe(3) is bonded to one O(5) and four equivalent O(4) atoms to form FeO5 square pyramids that share corners with four equivalent Fe(2)O6 octahedra,  a cornercorner with one Fe(3)O5 square pyramid, and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 12°. The Fe(3)-O(5) bond length is 1.90 Å. All Fe(3)-O(4) bond lengths are 1.86 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(1) atoms to form a mixture of distorted corner and face-sharing OSr4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Fe(1), and one Fe(2) atom to form a mixture of distorted corner, edge, and face-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), one Fe(2), and one Fe(3) atom. In the fifth O site, O(5) is bonded to four equivalent Sr(1) and two equivalent Fe(3) atoms to form distorted corner-sharing OSr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°.