CaFe2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(13), one O(3), and two equivalent O(1) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(8)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(7)O6 octahedra, corners with three equivalent Ca(5)O6 octahedra, and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-67°. In the second Ca site, Ca(2) is bonded to one O(2), one O(9), and two equivalent O(4) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with three equivalent Ca(3)O6 octahedra, and corners with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-71°. In the third Ca site, Ca(3) is bonded to one O(7), one O(9), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Fe(6)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. In the fourth Ca site, Ca(4) is bonded to one O(15), one O(6), and two equivalent O(10) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(8)O6 octahedra, corners with three equivalent Fe(5)O6 octahedra, and corners with four equivalent Fe(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-63°. In the fifth Ca site, Ca(5) is bonded to one O(17), one O(3), two equivalent O(1), and two equivalent O(16) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Fe(9)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(8)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(7)O6 octahedra. In the sixth Ca site, Ca(6) is bonded to one O(12), one O(18), and two equivalent O(11) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(8)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with two equivalent Fe(7)O6 octahedra, corners with three equivalent Fe(5)O6 octahedra, and corners with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-66°. There are nine inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Fe(9)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Fe(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. In the second Fe site, Fe(2) is bonded to one O(2), one O(8), two equivalent O(1), and two equivalent O(5) atoms to form FeO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Fe(9)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Fe(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. In the third Fe site, Fe(3) is bonded to one O(11), one O(12), one O(14), one O(4), one O(6), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Fe(6)O4 tetrahedra, corners with two equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. In the fourth Fe site, Fe(4) is bonded to one O(14), one O(6), two equivalent O(11), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Fe(6)O4 tetrahedra, corners with two equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. In the fifth Fe site, Fe(5) is bonded to one O(12), one O(15), two equivalent O(10), and two equivalent O(11) atoms to form FeO6 octahedra that share corners with three equivalent Ca(4)O4 tetrahedra, corners with three equivalent Ca(6)O4 tetrahedra,  an edgeedge with one Fe(4)O6 octahedra,  an edgeedge with one Fe(8)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(7)O6 octahedra. In the sixth Fe site, Fe(6) is bonded to one O(14), one O(7), and two equivalent O(5) atoms to form FeO4 tetrahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Ca(3)O6 octahedra, and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. In the seventh Fe site, Fe(7) is bonded to one O(10), one O(13), one O(15), one O(16), one O(17), and one O(18) atom to form FeO6 octahedra that share  a cornercorner with one Ca(1)O4 tetrahedra,  a cornercorner with one Ca(6)O4 tetrahedra, corners with two equivalent Ca(4)O4 tetrahedra, corners with two equivalent Fe(9)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, edges with two equivalent Fe(7)O6 octahedra, and edges with two equivalent Fe(8)O6 octahedra. In the eighth Fe site, Fe(8) is bonded to one O(13), one O(18), two equivalent O(10), and two equivalent O(16) atoms to form FeO6 octahedra that share  a cornercorner with one Ca(1)O4 tetrahedra,  a cornercorner with one Ca(6)O4 tetrahedra, corners with two equivalent Ca(4)O4 tetrahedra, corners with two equivalent Fe(9)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, and edges with four equivalent Fe(7)O6 octahedra. In the ninth Fe site, Fe(9) is bonded to one O(17), one O(8), and two equivalent O(16) atoms to form FeO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(8)O6 octahedra, corners with three equivalent Ca(5)O6 octahedra, and corners with four equivalent Fe(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-62°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(5), one Fe(1), and one Fe(2) atom to form distorted OCa2Fe2 trigonal pyramids that share  a cornercorner with one O(1)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(3)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(13)CaFe3 trigonal pyramid,  an edgeedge with one O(1)Ca2Fe2 trigonal pyramid,  an edgeedge with one O(3)Ca2Fe2 trigonal pyramid, and  an edgeedge with one O(2)CaFe3 trigonal pyramid. In the second O site, O(2) is bonded to one Ca(2), one Fe(2), and two equivalent Fe(1) atoms to form a mixture of distorted corner and edge-sharing OCaFe3 trigonal pyramids. In the third O site, O(3) is bonded to one Ca(1), one Ca(5), and two equivalent Fe(1) atoms to form distorted OCa2Fe2 trigonal pyramids that share  a cornercorner with one O(13)CaFe3 trigonal pyramid, corners with two equivalent O(1)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(2)CaFe3 trigonal pyramid, and edges with two equivalent O(1)Ca2Fe2 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ca(2), one Ca(3), one Fe(3), and one Fe(4) atom to form OCa2Fe2 trigonal pyramids that share  a cornercorner with one O(12)CaFe3 tetrahedra, corners with three equivalent O(11)CaFe3 tetrahedra,  a cornercorner with one O(4)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(9)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(2)CaFe3 trigonal pyramid,  an edgeedge with one O(4)Ca2Fe2 trigonal pyramid,  an edgeedge with one O(9)Ca2Fe2 trigonal pyramid, and  an edgeedge with one O(6)CaFe3 trigonal pyramid. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Ca(3), one Fe(1), one Fe(2), and one Fe(6) atom. In the sixth O site, O(6) is bonded to one Ca(4), one Fe(4), and two equivalent Fe(3) atoms to form distorted OCaFe3 trigonal pyramids that share  a cornercorner with one O(15)CaFe3 tetrahedra, corners with two equivalent O(10)CaFe3 tetrahedra, corners with two equivalent O(12)CaFe3 tetrahedra, corners with four equivalent O(11)CaFe3 tetrahedra,  an edgeedge with one O(9)Ca2Fe2 trigonal pyramid, and edges with two equivalent O(4)Ca2Fe2 trigonal pyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Ca(3), one Fe(6), and two equivalent Fe(1) atoms. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), one Fe(9), and two equivalent Fe(1) atoms. In the ninth O site, O(9) is bonded to one Ca(2), one Ca(3), and two equivalent Fe(3) atoms to form OCa2Fe2 trigonal pyramids that share corners with two equivalent O(11)CaFe3 tetrahedra, corners with two equivalent O(12)CaFe3 tetrahedra,  a cornercorner with one O(2)CaFe3 trigonal pyramid, corners with two equivalent O(4)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(6)CaFe3 trigonal pyramid, and edges with two equivalent O(4)Ca2Fe2 trigonal pyramids. In the tenth O site, O(10) is bonded to one Ca(4), one Fe(5), one Fe(7), and one Fe(8) atom to form a mixture of corner and edge-sharing OCaFe3 tetrahedra. In the eleventh O site, O(11) is bonded to one Ca(6), one Fe(3), one Fe(4), and one Fe(5) atom to form OCaFe3 tetrahedra that share  a cornercorner with one O(11)CaFe3 tetrahedra,  a cornercorner with one O(12)CaFe3 tetrahedra,  a cornercorner with one O(15)CaFe3 tetrahedra,  a cornercorner with one O(18)CaFe3 tetrahedra, corners with two equivalent O(10)CaFe3 tetrahedra,  a cornercorner with one O(9)Ca2Fe2 trigonal pyramid, corners with two equivalent O(6)CaFe3 trigonal pyramids, corners with three equivalent O(4)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(11)CaFe3 tetrahedra, and  an edgeedge with one O(12)CaFe3 tetrahedra. In the twelfth O site, O(12) is bonded to one Ca(6), one Fe(5), and two equivalent Fe(3) atoms to form distorted OCaFe3 tetrahedra that share  a cornercorner with one O(15)CaFe3 tetrahedra,  a cornercorner with one O(18)CaFe3 tetrahedra, corners with two equivalent O(10)CaFe3 tetrahedra, corners with two equivalent O(11)CaFe3 tetrahedra, corners with two equivalent O(4)Ca2Fe2 trigonal pyramids, corners with two equivalent O(9)Ca2Fe2 trigonal pyramids, corners with two equivalent O(6)CaFe3 trigonal pyramids, and edges with two equivalent O(11)CaFe3 tetrahedra. In the thirteenth O site, O(13) is bonded to one Ca(1), one Fe(8), and two equivalent Fe(7) atoms to form distorted OCaFe3 trigonal pyramids that share corners with three equivalent O(18)CaFe3 tetrahedra,  a cornercorner with one O(3)Ca2Fe2 trigonal pyramid, corners with two equivalent O(1)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(15)CaFe3 tetrahedra, and edges with two equivalent O(10)CaFe3 tetrahedra. In the fourteenth O site, O(14) is bonded in a distorted rectangular see-saw-like geometry to one Fe(4), one Fe(6), and two equivalent Fe(3) atoms. In the fifteenth O site, O(15) is bonded to one Ca(4), one Fe(5), and two equivalent Fe(7) atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Ca(5), one Fe(7), one Fe(8), and one Fe(9) atom. In the seventeenth O site, O(17) is bonded in a rectangular see-saw-like geometry to one Ca(5), one Fe(9), and two equivalent Fe(7) atoms. In the eighteenth O site, O(18) is bonded to one Ca(6), one Fe(8), and two equivalent Fe(7) atoms to form corner-sharing OCaFe3 tetrahedra.
CaFe2O4 is Spinel-like structured and crystallizes in the monoclinic Cm space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(13), one O(3), and two equivalent O(1) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(8)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(7)O6 octahedra, corners with three equivalent Ca(5)O6 octahedra, and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-67°. The Ca(1)-O(13) bond length is 2.27 Å. The Ca(1)-O(3) bond length is 2.17 Å. Both Ca(1)-O(1) bond lengths are 2.17 Å. In the second Ca site, Ca(2) is bonded to one O(2), one O(9), and two equivalent O(4) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with three equivalent Ca(3)O6 octahedra, and corners with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-71°. The Ca(2)-O(2) bond length is 2.24 Å. The Ca(2)-O(9) bond length is 2.18 Å. Both Ca(2)-O(4) bond lengths are 2.19 Å. In the third Ca site, Ca(3) is bonded to one O(7), one O(9), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Fe(6)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(4)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. The Ca(3)-O(7) bond length is 2.35 Å. The Ca(3)-O(9) bond length is 2.30 Å. Both Ca(3)-O(4) bond lengths are 2.30 Å. Both Ca(3)-O(5) bond lengths are 2.33 Å. In the fourth Ca site, Ca(4) is bonded to one O(15), one O(6), and two equivalent O(10) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with two equivalent Fe(8)O6 octahedra, corners with three equivalent Fe(5)O6 octahedra, and corners with four equivalent Fe(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-63°. The Ca(4)-O(15) bond length is 2.17 Å. The Ca(4)-O(6) bond length is 2.20 Å. Both Ca(4)-O(10) bond lengths are 2.18 Å. In the fifth Ca site, Ca(5) is bonded to one O(17), one O(3), two equivalent O(1), and two equivalent O(16) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Fe(9)O4 tetrahedra,  an edgeedge with one Fe(2)O6 octahedra,  an edgeedge with one Fe(8)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(7)O6 octahedra. The Ca(5)-O(17) bond length is 2.35 Å. The Ca(5)-O(3) bond length is 2.26 Å. Both Ca(5)-O(1) bond lengths are 2.26 Å. Both Ca(5)-O(16) bond lengths are 2.33 Å. In the sixth Ca site, Ca(6) is bonded to one O(12), one O(18), and two equivalent O(11) atoms to form CaO4 tetrahedra that share  a cornercorner with one Fe(8)O6 octahedra, corners with two equivalent Fe(4)O6 octahedra, corners with two equivalent Fe(7)O6 octahedra, corners with three equivalent Fe(5)O6 octahedra, and corners with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-66°. The Ca(6)-O(12) bond length is 2.20 Å. The Ca(6)-O(18) bond length is 2.32 Å. Both Ca(6)-O(11) bond lengths are 2.21 Å. There are nine inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(8) atom to form FeO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Fe(9)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Fe(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The Fe(1)-O(1) bond length is 1.99 Å. The Fe(1)-O(2) bond length is 2.07 Å. The Fe(1)-O(3) bond length is 1.98 Å. The Fe(1)-O(5) bond length is 2.15 Å. The Fe(1)-O(7) bond length is 2.16 Å. The Fe(1)-O(8) bond length is 2.24 Å. In the second Fe site, Fe(2) is bonded to one O(2), one O(8), two equivalent O(1), and two equivalent O(5) atoms to form FeO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Fe(9)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Fe(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Fe(1)O6 octahedra. The Fe(2)-O(2) bond length is 2.06 Å. The Fe(2)-O(8) bond length is 2.28 Å. Both Fe(2)-O(1) bond lengths are 1.98 Å. Both Fe(2)-O(5) bond lengths are 2.15 Å. In the third Fe site, Fe(3) is bonded to one O(11), one O(12), one O(14), one O(4), one O(6), and one O(9) atom to form FeO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Fe(6)O4 tetrahedra, corners with two equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(4)O6 octahedra. The Fe(3)-O(11) bond length is 2.07 Å. The Fe(3)-O(12) bond length is 2.07 Å. The Fe(3)-O(14) bond length is 2.21 Å. The Fe(3)-O(4) bond length is 1.99 Å. The Fe(3)-O(6) bond length is 2.16 Å. The Fe(3)-O(9) bond length is 2.00 Å. In the fourth Fe site, Fe(4) is bonded to one O(14), one O(6), two equivalent O(11), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Fe(6)O4 tetrahedra, corners with two equivalent Ca(2)O4 tetrahedra, corners with two equivalent Ca(6)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The Fe(4)-O(14) bond length is 2.61 Å. The Fe(4)-O(6) bond length is 2.02 Å. Both Fe(4)-O(11) bond lengths are 2.04 Å. Both Fe(4)-O(4) bond lengths are 1.97 Å. In the fifth Fe site, Fe(5) is bonded to one O(12), one O(15), two equivalent O(10), and two equivalent O(11) atoms to form FeO6 octahedra that share corners with three equivalent Ca(4)O4 tetrahedra, corners with three equivalent Ca(6)O4 tetrahedra,  an edgeedge with one Fe(4)O6 octahedra,  an edgeedge with one Fe(8)O6 octahedra, edges with two equivalent Fe(3)O6 octahedra, and edges with two equivalent Fe(7)O6 octahedra. The Fe(5)-O(12) bond length is 2.00 Å. The Fe(5)-O(15) bond length is 2.11 Å. Both Fe(5)-O(10) bond lengths are 2.07 Å. Both Fe(5)-O(11) bond lengths are 2.00 Å. In the sixth Fe site, Fe(6) is bonded to one O(14), one O(7), and two equivalent O(5) atoms to form FeO4 tetrahedra that share  a cornercorner with one Fe(4)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(3)O6 octahedra, corners with three equivalent Ca(3)O6 octahedra, and corners with four equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. The Fe(6)-O(14) bond length is 1.98 Å. The Fe(6)-O(7) bond length is 1.98 Å. Both Fe(6)-O(5) bond lengths are 1.97 Å. In the seventh Fe site, Fe(7) is bonded to one O(10), one O(13), one O(15), one O(16), one O(17), and one O(18) atom to form FeO6 octahedra that share  a cornercorner with one Ca(1)O4 tetrahedra,  a cornercorner with one Ca(6)O4 tetrahedra, corners with two equivalent Ca(4)O4 tetrahedra, corners with two equivalent Fe(9)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, edges with two equivalent Fe(7)O6 octahedra, and edges with two equivalent Fe(8)O6 octahedra. The Fe(7)-O(10) bond length is 2.02 Å. The Fe(7)-O(13) bond length is 2.08 Å. The Fe(7)-O(15) bond length is 2.03 Å. The Fe(7)-O(16) bond length is 2.18 Å. The Fe(7)-O(17) bond length is 2.16 Å. The Fe(7)-O(18) bond length is 2.06 Å. In the eighth Fe site, Fe(8) is bonded to one O(13), one O(18), two equivalent O(10), and two equivalent O(16) atoms to form FeO6 octahedra that share  a cornercorner with one Ca(1)O4 tetrahedra,  a cornercorner with one Ca(6)O4 tetrahedra, corners with two equivalent Ca(4)O4 tetrahedra, corners with two equivalent Fe(9)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Fe(5)O6 octahedra, and edges with four equivalent Fe(7)O6 octahedra. The Fe(8)-O(13) bond length is 2.06 Å. The Fe(8)-O(18) bond length is 2.08 Å. Both Fe(8)-O(10) bond lengths are 2.01 Å. Both Fe(8)-O(16) bond lengths are 2.16 Å. In the ninth Fe site, Fe(9) is bonded to one O(17), one O(8), and two equivalent O(16) atoms to form FeO4 tetrahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Fe(1)O6 octahedra, corners with two equivalent Fe(8)O6 octahedra, corners with three equivalent Ca(5)O6 octahedra, and corners with four equivalent Fe(7)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-62°. The Fe(9)-O(17) bond length is 1.95 Å. The Fe(9)-O(8) bond length is 2.04 Å. Both Fe(9)-O(16) bond lengths are 1.96 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(5), one Fe(1), and one Fe(2) atom to form distorted OCa2Fe2 trigonal pyramids that share  a cornercorner with one O(1)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(3)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(13)CaFe3 trigonal pyramid,  an edgeedge with one O(1)Ca2Fe2 trigonal pyramid,  an edgeedge with one O(3)Ca2Fe2 trigonal pyramid, and  an edgeedge with one O(2)CaFe3 trigonal pyramid. In the second O site, O(2) is bonded to one Ca(2), one Fe(2), and two equivalent Fe(1) atoms to form a mixture of distorted corner and edge-sharing OCaFe3 trigonal pyramids. In the third O site, O(3) is bonded to one Ca(1), one Ca(5), and two equivalent Fe(1) atoms to form distorted OCa2Fe2 trigonal pyramids that share  a cornercorner with one O(13)CaFe3 trigonal pyramid, corners with two equivalent O(1)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(2)CaFe3 trigonal pyramid, and edges with two equivalent O(1)Ca2Fe2 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ca(2), one Ca(3), one Fe(3), and one Fe(4) atom to form OCa2Fe2 trigonal pyramids that share  a cornercorner with one O(12)CaFe3 tetrahedra, corners with three equivalent O(11)CaFe3 tetrahedra,  a cornercorner with one O(4)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(9)Ca2Fe2 trigonal pyramid,  a cornercorner with one O(2)CaFe3 trigonal pyramid,  an edgeedge with one O(4)Ca2Fe2 trigonal pyramid,  an edgeedge with one O(9)Ca2Fe2 trigonal pyramid, and  an edgeedge with one O(6)CaFe3 trigonal pyramid. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Ca(3), one Fe(1), one Fe(2), and one Fe(6) atom. In the sixth O site, O(6) is bonded to one Ca(4), one Fe(4), and two equivalent Fe(3) atoms to form distorted OCaFe3 trigonal pyramids that share  a cornercorner with one O(15)CaFe3 tetrahedra, corners with two equivalent O(10)CaFe3 tetrahedra, corners with two equivalent O(12)CaFe3 tetrahedra, corners with four equivalent O(11)CaFe3 tetrahedra,  an edgeedge with one O(9)Ca2Fe2 trigonal pyramid, and edges with two equivalent O(4)Ca2Fe2 trigonal pyramids. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Ca(3), one Fe(6), and two equivalent Fe(1) atoms. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one Fe(2), one Fe(9), and two equivalent Fe(1) atoms. In the ninth O site, O(9) is bonded to one Ca(2), one Ca(3), and two equivalent Fe(3) atoms to form OCa2Fe2 trigonal pyramids that share corners with two equivalent O(11)CaFe3 tetrahedra, corners with two equivalent O(12)CaFe3 tetrahedra,  a cornercorner with one O(2)CaFe3 trigonal pyramid, corners with two equivalent O(4)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(6)CaFe3 trigonal pyramid, and edges with two equivalent O(4)Ca2Fe2 trigonal pyramids. In the tenth O site, O(10) is bonded to one Ca(4), one Fe(5), one Fe(7), and one Fe(8) atom to form a mixture of corner and edge-sharing OCaFe3 tetrahedra. In the eleventh O site, O(11) is bonded to one Ca(6), one Fe(3), one Fe(4), and one Fe(5) atom to form OCaFe3 tetrahedra that share  a cornercorner with one O(11)CaFe3 tetrahedra,  a cornercorner with one O(12)CaFe3 tetrahedra,  a cornercorner with one O(15)CaFe3 tetrahedra,  a cornercorner with one O(18)CaFe3 tetrahedra, corners with two equivalent O(10)CaFe3 tetrahedra,  a cornercorner with one O(9)Ca2Fe2 trigonal pyramid, corners with two equivalent O(6)CaFe3 trigonal pyramids, corners with three equivalent O(4)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(11)CaFe3 tetrahedra, and  an edgeedge with one O(12)CaFe3 tetrahedra. In the twelfth O site, O(12) is bonded to one Ca(6), one Fe(5), and two equivalent Fe(3) atoms to form distorted OCaFe3 tetrahedra that share  a cornercorner with one O(15)CaFe3 tetrahedra,  a cornercorner with one O(18)CaFe3 tetrahedra, corners with two equivalent O(10)CaFe3 tetrahedra, corners with two equivalent O(11)CaFe3 tetrahedra, corners with two equivalent O(4)Ca2Fe2 trigonal pyramids, corners with two equivalent O(9)Ca2Fe2 trigonal pyramids, corners with two equivalent O(6)CaFe3 trigonal pyramids, and edges with two equivalent O(11)CaFe3 tetrahedra. In the thirteenth O site, O(13) is bonded to one Ca(1), one Fe(8), and two equivalent Fe(7) atoms to form distorted OCaFe3 trigonal pyramids that share corners with three equivalent O(18)CaFe3 tetrahedra,  a cornercorner with one O(3)Ca2Fe2 trigonal pyramid, corners with two equivalent O(1)Ca2Fe2 trigonal pyramids,  an edgeedge with one O(15)CaFe3 tetrahedra, and edges with two equivalent O(10)CaFe3 tetrahedra. In the fourteenth O site, O(14) is bonded in a distorted rectangular see-saw-like geometry to one Fe(4), one Fe(6), and two equivalent Fe(3) atoms. In the fifteenth O site, O(15) is bonded to one Ca(4), one Fe(5), and two equivalent Fe(7) atoms to form a mixture of distorted corner and edge-sharing OCaFe3 tetrahedra. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Ca(5), one Fe(7), one Fe(8), and one Fe(9) atom. In the seventeenth O site, O(17) is bonded in a rectangular see-saw-like geometry to one Ca(5), one Fe(9), and two equivalent Fe(7) atoms. In the eighteenth O site, O(18) is bonded to one Ca(6), one Fe(8), and two equivalent Fe(7) atoms to form corner-sharing OCaFe3 tetrahedra.