CaFe2O4 crystallizes in the monoclinic Cm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(6), and two equivalent O(7) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(5), and two equivalent O(8) atoms. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 52-56°. In the second Fe site, Fe(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(3), two equivalent O(1), and two equivalent O(7) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O5 square pyramids. The corner-sharing octahedral tilt angles range from 51-56°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Fe(3), and two equivalent Fe(4) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Fe(1), and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Fe(4), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Fe(1) atoms. In the sixth O site, O(6) is bonded to two equivalent Ca(1), one Fe(3), and two equivalent Fe(2) atoms to form distorted edge-sharing OCa2Fe3 trigonal bipyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Fe(4) atoms. In the eighth O site, O(8) is bonded to two equivalent Ca(2), one Fe(2), and two equivalent Fe(3) atoms to form edge-sharing OCa2Fe3 square pyramids.
CaFe2O4 crystallizes in the monoclinic Cm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to one O(2), one O(4), two equivalent O(6), and two equivalent O(7) atoms. The Ca(1)-O(2) bond length is 2.56 Å. The Ca(1)-O(4) bond length is 2.70 Å. Both Ca(1)-O(6) bond lengths are 2.28 Å. Both Ca(1)-O(7) bond lengths are 2.29 Å. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), two equivalent O(5), and two equivalent O(8) atoms. The Ca(2)-O(1) bond length is 2.91 Å. The Ca(2)-O(3) bond length is 2.46 Å. Both Ca(2)-O(5) bond lengths are 2.29 Å. Both Ca(2)-O(8) bond lengths are 2.28 Å. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(2), two equivalent O(4), and two equivalent O(5) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(1)O5 square pyramids. The corner-sharing octahedral tilt angles range from 52-56°. The Fe(1)-O(2) bond length is 1.95 Å. Both Fe(1)-O(4) bond lengths are 2.01 Å. Both Fe(1)-O(5) bond lengths are 2.09 Å. In the second Fe site, Fe(2) is bonded to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. The Fe(2)-O(4) bond length is 2.01 Å. The Fe(2)-O(8) bond length is 2.06 Å. Both Fe(2)-O(3) bond lengths are 2.04 Å. Both Fe(2)-O(6) bond lengths are 2.11 Å. In the third Fe site, Fe(3) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(8) atoms to form FeO6 octahedra that share corners with two equivalent Fe(1)O5 square pyramids, corners with two equivalent Fe(4)O5 square pyramids, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. The Fe(3)-O(1) bond length is 1.98 Å. The Fe(3)-O(6) bond length is 2.05 Å. Both Fe(3)-O(2) bond lengths are 2.03 Å. Both Fe(3)-O(8) bond lengths are 2.12 Å. In the fourth Fe site, Fe(4) is bonded to one O(3), two equivalent O(1), and two equivalent O(7) atoms to form distorted FeO5 square pyramids that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O5 square pyramids. The corner-sharing octahedral tilt angles range from 51-56°. The Fe(4)-O(3) bond length is 1.96 Å. Both Fe(4)-O(1) bond lengths are 1.99 Å. Both Fe(4)-O(7) bond lengths are 2.09 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(2), one Fe(3), and two equivalent Fe(4) atoms. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Ca(1), one Fe(1), and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Ca(2), one Fe(4), and two equivalent Fe(2) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Fe(2), and two equivalent Fe(1) atoms. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(2) and two equivalent Fe(1) atoms. In the sixth O site, O(6) is bonded to two equivalent Ca(1), one Fe(3), and two equivalent Fe(2) atoms to form distorted edge-sharing OCa2Fe3 trigonal bipyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to two equivalent Ca(1) and two equivalent Fe(4) atoms. In the eighth O site, O(8) is bonded to two equivalent Ca(2), one Fe(2), and two equivalent Fe(3) atoms to form edge-sharing OCa2Fe3 square pyramids.