SrEu2Fe2O7 crystallizes in the tetragonal P4_2/mnm space group. Sr(1) is bonded to two equivalent O(2), two equivalent O(4), four equivalent O(3), and four equivalent O(5) atoms to form distorted SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Fe(1)O6 octahedra. Eu(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), two equivalent O(5), and three equivalent O(1) atoms. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with five equivalent Fe(1)O6 octahedra and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 7-24°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Eu(1) and one Fe(1) atom. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms to form a mixture of distorted face, corner, and edge-sharing OSr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles are 60°. In the third O site, O(3) is bonded in a 6-coordinate geometry to four equivalent Sr(1) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms to form a mixture of distorted face, corner, and edge-sharing OSr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-60°.
SrEu2Fe2O7 crystallizes in the tetragonal P4_2/mnm space group. Sr(1) is bonded to two equivalent O(2), two equivalent O(4), four equivalent O(3), and four equivalent O(5) atoms to form distorted SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Fe(1)O6 octahedra. Both Sr(1)-O(2) bond lengths are 2.63 Å. Both Sr(1)-O(4) bond lengths are 3.14 Å. There are two shorter (2.63 Å) and two longer (2.98 Å) Sr(1)-O(3) bond lengths. All Sr(1)-O(5) bond lengths are 2.88 Å. Eu(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), two equivalent O(5), and three equivalent O(1) atoms. The Eu(1)-O(2) bond length is 2.62 Å. The Eu(1)-O(4) bond length is 2.49 Å. Both Eu(1)-O(5) bond lengths are 2.54 Å. There is one shorter (2.30 Å) and two longer (2.45 Å) Eu(1)-O(1) bond lengths. Fe(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with five equivalent Fe(1)O6 octahedra and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 7-24°. The Fe(1)-O(1) bond length is 2.14 Å. The Fe(1)-O(2) bond length is 2.02 Å. The Fe(1)-O(3) bond length is 2.00 Å. The Fe(1)-O(4) bond length is 1.99 Å. Both Fe(1)-O(5) bond lengths are 1.98 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to three equivalent Eu(1) and one Fe(1) atom. In the second O site, O(2) is bonded to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms to form a mixture of distorted face, corner, and edge-sharing OSr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles are 60°. In the third O site, O(3) is bonded in a 6-coordinate geometry to four equivalent Sr(1) and two equivalent Fe(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms to form a mixture of distorted face, corner, and edge-sharing OSr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 2-60°.