SrEu2Fe2O7 crystallizes in the orthorhombic Cmcm space group. Sr(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form 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 9-coordinate geometry to two equivalent O(2), two equivalent O(3), and five equivalent O(4) atoms. Fe(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) 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 1-7°. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(1) and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(4)Eu5Fe octahedra, corners with four equivalent O(1)Sr4Fe2 octahedra, corners with eight equivalent O(3)Sr2Eu2Fe2 octahedra, edges with four equivalent O(1)Sr4Fe2 octahedra, and faces with four equivalent O(3)Sr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms to form distorted OSr2Eu2Fe2 octahedra that share corners with two equivalent O(3)Sr2Eu2Fe2 octahedra, corners with four equivalent O(1)Sr4Fe2 octahedra, corners with six equivalent O(4)Eu5Fe octahedra,  an edgeedge with one O(3)Sr2Eu2Fe2 octahedra, faces with two equivalent O(4)Eu5Fe octahedra, faces with two equivalent O(3)Sr2Eu2Fe2 octahedra, and faces with two equivalent O(1)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 45-60°. In the fourth O site, O(4) is bonded to five equivalent Eu(1) and one Fe(1) atom to form distorted OEu5Fe octahedra that share  a cornercorner with one O(1)Sr4Fe2 octahedra, corners with four equivalent O(4)Eu5Fe octahedra, corners with six equivalent O(3)Sr2Eu2Fe2 octahedra, edges with eight equivalent O(4)Eu5Fe octahedra, and faces with two equivalent O(3)Sr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 1-54°.
SrEu2Fe2O7 crystallizes in the orthorhombic Cmcm space group. Sr(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) atoms to form 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. There are a spread of Sr(1)-O(1) bond distances ranging from 2.65-2.78 Å. All Sr(1)-O(2) bond lengths are 2.82 Å. All Sr(1)-O(3) bond lengths are 2.73 Å. Eu(1) is bonded in a 9-coordinate geometry to two equivalent O(2), two equivalent O(3), and five equivalent O(4) atoms. Both Eu(1)-O(2) bond lengths are 2.53 Å. Both Eu(1)-O(3) bond lengths are 2.56 Å. There are a spread of Eu(1)-O(4) bond distances ranging from 2.34-2.87 Å. Fe(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) 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 1-7°. The Fe(1)-O(1) bond length is 1.94 Å. The Fe(1)-O(4) bond length is 2.07 Å. Both Fe(1)-O(2) bond lengths are 1.92 Å. Both Fe(1)-O(3) bond lengths are 1.92 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(1) and two equivalent Fe(1) atoms to form distorted OSr4Fe2 octahedra that share corners with two equivalent O(4)Eu5Fe octahedra, corners with four equivalent O(1)Sr4Fe2 octahedra, corners with eight equivalent O(3)Sr2Eu2Fe2 octahedra, edges with four equivalent O(1)Sr4Fe2 octahedra, and faces with four equivalent O(3)Sr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms. In the third O site, O(3) is bonded to two equivalent Sr(1), two equivalent Eu(1), and two equivalent Fe(1) atoms to form distorted OSr2Eu2Fe2 octahedra that share corners with two equivalent O(3)Sr2Eu2Fe2 octahedra, corners with four equivalent O(1)Sr4Fe2 octahedra, corners with six equivalent O(4)Eu5Fe octahedra,  an edgeedge with one O(3)Sr2Eu2Fe2 octahedra, faces with two equivalent O(4)Eu5Fe octahedra, faces with two equivalent O(3)Sr2Eu2Fe2 octahedra, and faces with two equivalent O(1)Sr4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 45-60°. In the fourth O site, O(4) is bonded to five equivalent Eu(1) and one Fe(1) atom to form distorted OEu5Fe octahedra that share  a cornercorner with one O(1)Sr4Fe2 octahedra, corners with four equivalent O(4)Eu5Fe octahedra, corners with six equivalent O(3)Sr2Eu2Fe2 octahedra, edges with eight equivalent O(4)Eu5Fe octahedra, and faces with two equivalent O(3)Sr2Eu2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 1-54°.