Ca2Fe2O5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form distorted CaO6 pentagonal pyramids that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Ca(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 20-76°. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and two equivalent O(3) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms. In the second Fe site, Fe(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Ca(1)O6 pentagonal pyramids, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 29°. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent Ca(1)O6 pentagonal pyramids, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 29°. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Ca(2), two equivalent Ca(1), one Fe(1), and one Fe(3) atom to form a mixture of distorted edge and corner-sharing OCa3Fe2 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Fe(1), and one Fe(3) atom. In the third O site, O(3) is bonded to one Ca(1), two equivalent Ca(2), one Fe(1), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing OCa3Fe2 trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Fe(2), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Fe(1), one Fe(2), and one Fe(3) atom.
Ca2Fe2O5 crystallizes in the triclinic P-1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form distorted CaO6 pentagonal pyramids that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(3)O6 octahedra, and  an edgeedge with one Ca(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 20-76°. The Ca(1)-O(2) bond length is 2.48 Å. The Ca(1)-O(3) bond length is 2.63 Å. The Ca(1)-O(4) bond length is 2.73 Å. The Ca(1)-O(5) bond length is 2.32 Å. There is one shorter (2.30 Å) and one longer (2.44 Å) Ca(1)-O(1) bond length. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and two equivalent O(3) atoms. The Ca(2)-O(1) bond length is 2.54 Å. The Ca(2)-O(2) bond length is 2.35 Å. The Ca(2)-O(4) bond length is 2.45 Å. The Ca(2)-O(5) bond length is 2.47 Å. There is one shorter (2.30 Å) and one longer (2.62 Å) Ca(2)-O(3) bond length. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and two equivalent O(4) atoms. The Fe(1)-O(1) bond length is 2.04 Å. The Fe(1)-O(2) bond length is 1.95 Å. The Fe(1)-O(3) bond length is 2.13 Å. The Fe(1)-O(5) bond length is 2.39 Å. There is one shorter (2.01 Å) and one longer (2.10 Å) Fe(1)-O(4) bond length. In the second Fe site, Fe(2) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form FeO6 octahedra that share corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Ca(1)O6 pentagonal pyramids, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 29°. Both Fe(2)-O(3) bond lengths are 1.95 Å. Both Fe(2)-O(4) bond lengths are 2.26 Å. Both Fe(2)-O(5) bond lengths are 1.97 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(5) atoms to form distorted FeO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with four equivalent Ca(1)O6 pentagonal pyramids, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 29°. Both Fe(3)-O(1) bond lengths are 2.28 Å. Both Fe(3)-O(2) bond lengths are 2.06 Å. Both Fe(3)-O(5) bond lengths are 1.93 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Ca(2), two equivalent Ca(1), one Fe(1), and one Fe(3) atom to form a mixture of distorted edge and corner-sharing OCa3Fe2 trigonal bipyramids. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Fe(1), and one Fe(3) atom. In the third O site, O(3) is bonded to one Ca(1), two equivalent Ca(2), one Fe(1), and one Fe(2) atom to form a mixture of distorted edge and corner-sharing OCa3Fe2 trigonal bipyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Fe(2), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Ca(1), one Ca(2), one Fe(1), one Fe(2), and one Fe(3) atom.