SrCa4(FeO2)5 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. In the second Ca site, Ca(2) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. In the second Fe site, Fe(2) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. In the third Fe site, Fe(3) is bonded in a square co-planar geometry to four equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Ca(1), and two equivalent Fe(1) atoms to form OSr2Ca2Fe2 octahedra that share corners with six equivalent O(2)Ca4Fe2 octahedra, corners with eight equivalent O(1)Sr2Ca2Fe2 octahedra,  an edgeedge with one O(2)Ca4Fe2 octahedra, edges with three equivalent O(1)Sr2Ca2Fe2 octahedra, and faces with four equivalent O(1)Sr2Ca2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the second O site, O(2) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Fe(2) atoms to form OCa4Fe2 octahedra that share corners with two equivalent O(2)Ca4Fe2 octahedra, corners with six equivalent O(3)Ca4Fe2 octahedra, corners with six equivalent O(1)Sr2Ca2Fe2 octahedra,  an edgeedge with one O(3)Ca4Fe2 octahedra,  an edgeedge with one O(1)Sr2Ca2Fe2 octahedra, edges with two equivalent O(2)Ca4Fe2 octahedra, and faces with four equivalent O(2)Ca4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the third O site, O(3) is bonded to four equivalent Ca(2) and two equivalent Fe(3) atoms to form a mixture of face, corner, and edge-sharing OCa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°.
SrCa4(FeO2)5 crystallizes in the tetragonal P4/mmm space group. Sr(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Sr(1)-O(1) bond lengths are 2.66 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Ca(1)-O(1) bond lengths are 2.56 Å. All Ca(1)-O(2) bond lengths are 2.58 Å. In the second Ca site, Ca(2) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Ca(2)-O(2) bond lengths are 2.59 Å. All Ca(2)-O(3) bond lengths are 2.59 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. All Fe(1)-O(1) bond lengths are 2.01 Å. In the second Fe site, Fe(2) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. All Fe(2)-O(2) bond lengths are 2.01 Å. In the third Fe site, Fe(3) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Fe(3)-O(3) bond lengths are 2.01 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Ca(1), and two equivalent Fe(1) atoms to form OSr2Ca2Fe2 octahedra that share corners with six equivalent O(2)Ca4Fe2 octahedra, corners with eight equivalent O(1)Sr2Ca2Fe2 octahedra,  an edgeedge with one O(2)Ca4Fe2 octahedra, edges with three equivalent O(1)Sr2Ca2Fe2 octahedra, and faces with four equivalent O(1)Sr2Ca2Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the second O site, O(2) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Fe(2) atoms to form OCa4Fe2 octahedra that share corners with two equivalent O(2)Ca4Fe2 octahedra, corners with six equivalent O(3)Ca4Fe2 octahedra, corners with six equivalent O(1)Sr2Ca2Fe2 octahedra,  an edgeedge with one O(3)Ca4Fe2 octahedra,  an edgeedge with one O(1)Sr2Ca2Fe2 octahedra, edges with two equivalent O(2)Ca4Fe2 octahedra, and faces with four equivalent O(2)Ca4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°. In the third O site, O(3) is bonded to four equivalent Ca(2) and two equivalent Fe(3) atoms to form a mixture of face, corner, and edge-sharing OCa4Fe2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°.