Ca2Fe2O5 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-16°. In the second Fe site, Fe(2) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and  an edgeedge with one Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 40°. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Fe(1) atoms to form distorted OCa4Fe2 octahedra that share corners with two equivalent O(1)Ca4Fe2 octahedra, corners with four equivalent O(4)Ca2Fe2 trigonal pyramids, edges with two equivalent O(1)Ca4Fe2 octahedra, and faces with four equivalent O(2)Ca4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to four equivalent Ca(1) and two equivalent Fe(1) atoms to form distorted OCa4Fe2 octahedra that share corners with two equivalent O(2)Ca4Fe2 octahedra, corners with four equivalent O(4)Ca2Fe2 trigonal pyramids, edges with two equivalent O(2)Ca4Fe2 octahedra, and faces with four equivalent O(1)Ca4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca(1), one Fe(1), and one Fe(2) atom. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Fe(2) atoms to form OCa2Fe2 trigonal pyramids that share corners with four equivalent O(1)Ca4Fe2 octahedra, corners with four equivalent O(2)Ca4Fe2 octahedra, and  an edgeedge with one O(4)Ca2Fe2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 22-81°.
Ca2Fe2O5 crystallizes in the monoclinic C2/m space group. Ca(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. The Ca(1)-O(4) bond length is 2.30 Å. Both Ca(1)-O(1) bond lengths are 2.57 Å. There is one shorter (2.45 Å) and one longer (2.62 Å) Ca(1)-O(2) bond length. There is one shorter (2.35 Å) and one longer (2.54 Å) Ca(1)-O(3) bond length. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share corners with four equivalent Fe(1)O6 octahedra and corners with two equivalent Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 8-16°. Both Fe(1)-O(1) bond lengths are 1.99 Å. Both Fe(1)-O(2) bond lengths are 2.00 Å. Both Fe(1)-O(3) bond lengths are 2.12 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(3) and two equivalent O(4) atoms to form FeO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra and  an edgeedge with one Fe(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 40°. Both Fe(2)-O(3) bond lengths are 1.86 Å. There is one shorter (1.97 Å) and one longer (1.99 Å) Fe(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Fe(1) atoms to form distorted OCa4Fe2 octahedra that share corners with two equivalent O(1)Ca4Fe2 octahedra, corners with four equivalent O(4)Ca2Fe2 trigonal pyramids, edges with two equivalent O(1)Ca4Fe2 octahedra, and faces with four equivalent O(2)Ca4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to four equivalent Ca(1) and two equivalent Fe(1) atoms to form distorted OCa4Fe2 octahedra that share corners with two equivalent O(2)Ca4Fe2 octahedra, corners with four equivalent O(4)Ca2Fe2 trigonal pyramids, edges with two equivalent O(2)Ca4Fe2 octahedra, and faces with four equivalent O(1)Ca4Fe2 octahedra. The corner-sharing octahedra are not tilted. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca(1), one Fe(1), and one Fe(2) atom. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Fe(2) atoms to form OCa2Fe2 trigonal pyramids that share corners with four equivalent O(1)Ca4Fe2 octahedra, corners with four equivalent O(2)Ca4Fe2 octahedra, and  an edgeedge with one O(4)Ca2Fe2 trigonal pyramid. The corner-sharing octahedral tilt angles range from 22-81°.