CaCo2O4 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(9) and three equivalent O(1) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Co(5)O6 octahedra, and corners with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-69°. In the second Ca site, Ca(2) is bonded to one O(2) and three equivalent O(3) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and corners with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-74°. In the third Ca site, Ca(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form distorted CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Co(4)O4 tetrahedra, edges with three equivalent Co(1)O6 octahedra, and edges with three equivalent Co(2)O6 octahedra. In the fourth Ca site, Ca(4) is bonded to one O(5) and three equivalent O(7) atoms to form distorted CaO4 tetrahedra that share corners with three equivalent Co(2)O6 octahedra, corners with three equivalent Co(3)O6 octahedra, and corners with six equivalent Co(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-68°. In the fifth Ca site, Ca(5) is bonded to three equivalent O(1) and three equivalent O(11) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Co(6)O4 tetrahedra, edges with three equivalent Co(1)O6 octahedra, and edges with three equivalent Co(5)O6 octahedra. In the sixth Ca site, Ca(6) is bonded to one O(12) and three equivalent O(8) atoms to form CaO4 tetrahedra that share corners with three equivalent Co(3)O6 octahedra, corners with three equivalent Co(5)O6 octahedra, and corners with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-65°. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form CoO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Co(6)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Co(4)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Co(1)O6 octahedra. In the second Co site, Co(2) is bonded to one O(10), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form CoO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Co(4)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 Co(3)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. In the third Co site, Co(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form CoO6 octahedra that share corners with three equivalent Ca(4)O4 tetrahedra, corners with three equivalent Ca(6)O4 tetrahedra, edges with three equivalent Co(2)O6 octahedra, and edges with three equivalent Co(5)O6 octahedra. In the fourth Co site, Co(4) is bonded to one O(10) and three equivalent O(4) atoms to form CoO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, and corners with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-63°. In the fifth Co site, Co(5) is bonded to one O(12), one O(9), two equivalent O(11), and two equivalent O(7) atoms to form CoO6 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 Co(6)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Co(3)O6 octahedra, and edges with four equivalent Co(5)O6 octahedra. In the sixth Co site, Co(6) is bonded to one O(6) and three equivalent O(11) atoms to form CoO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and corners with six equivalent Co(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-67°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(5), and two equivalent Co(1) atoms to form distorted OCa2Co2 trigonal pyramids that share  a cornercorner with one O(9)CaCo3 trigonal pyramid, corners with two equivalent O(1)Ca2Co2 trigonal pyramids, corners with four equivalent O(4)CaCo3 trigonal pyramids,  an edgeedge with one O(2)CaCo3 trigonal pyramid, and edges with two equivalent O(1)Ca2Co2 trigonal pyramids. In the second O site, O(2) is bonded to one Ca(2) and three equivalent Co(1) atoms to form distorted OCaCo3 trigonal pyramids that share corners with three equivalent O(3)Ca2Co2 trigonal pyramids, corners with six equivalent O(4)CaCo3 trigonal pyramids, and edges with three equivalent O(1)Ca2Co2 trigonal pyramids. In the third O site, O(3) is bonded to one Ca(2), one Ca(3), and two equivalent Co(2) atoms to form OCa2Co2 trigonal pyramids that share corners with four equivalent O(8)CaCo3 tetrahedra,  a cornercorner with one O(2)CaCo3 trigonal pyramid, corners with two equivalent O(3)Ca2Co2 trigonal pyramids, corners with three equivalent O(4)CaCo3 trigonal pyramids,  an edgeedge with one O(5)CaCo3 trigonal pyramid, and edges with two equivalent O(3)Ca2Co2 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ca(3), one Co(4), and two equivalent Co(1) atoms to form distorted OCaCo3 trigonal pyramids that share corners with two equivalent O(2)CaCo3 trigonal pyramids, corners with two equivalent O(4)CaCo3 trigonal pyramids, corners with three equivalent O(3)Ca2Co2 trigonal pyramids, corners with four equivalent O(1)Ca2Co2 trigonal pyramids, and edges with two equivalent O(4)CaCo3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Ca(4) and three equivalent Co(2) atoms to form distorted OCaCo3 trigonal pyramids that share corners with three equivalent O(7)CaCo3 tetrahedra, corners with six equivalent O(8)CaCo3 tetrahedra, and edges with three equivalent O(3)Ca2Co2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Co(6) and three equivalent Co(1) atoms. In the seventh O site, O(7) is bonded to one Ca(4), one Co(3), and two equivalent Co(5) atoms to form a mixture of corner and edge-sharing OCaCo3 tetrahedra. In the eighth O site, O(8) is bonded to one Ca(6), one Co(3), and two equivalent Co(2) atoms to form OCaCo3 tetrahedra that share  a cornercorner with one O(12)CaCo3 tetrahedra, corners with two equivalent O(8)CaCo3 tetrahedra, corners with three equivalent O(7)CaCo3 tetrahedra, corners with two equivalent O(5)CaCo3 trigonal pyramids, corners with four equivalent O(3)Ca2Co2 trigonal pyramids, and edges with two equivalent O(8)CaCo3 tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1) and three equivalent Co(5) atoms to form distorted OCaCo3 trigonal pyramids that share corners with three equivalent O(12)CaCo3 tetrahedra, corners with three equivalent O(1)Ca2Co2 trigonal pyramids, and edges with three equivalent O(7)CaCo3 tetrahedra. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Co(4) and three equivalent Co(2) atoms. In the eleventh O site, O(11) is bonded in a distorted rectangular see-saw-like geometry to one Ca(5), one Co(6), and two equivalent Co(5) atoms. In the twelfth O site, O(12) is bonded to one Ca(6) and three equivalent Co(5) atoms to form corner-sharing OCaCo3 tetrahedra.
CaCo2O4 is Spinel-like structured and crystallizes in the trigonal P3m1 space group. There are six inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(9) and three equivalent O(1) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Co(5)O6 octahedra, and corners with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-69°. The Ca(1)-O(9) bond length is 2.23 Å. All Ca(1)-O(1) bond lengths are 2.17 Å. In the second Ca site, Ca(2) is bonded to one O(2) and three equivalent O(3) atoms to form CaO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and corners with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-74°. The Ca(2)-O(2) bond length is 2.17 Å. All Ca(2)-O(3) bond lengths are 2.19 Å. In the third Ca site, Ca(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form distorted CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Co(4)O4 tetrahedra, edges with three equivalent Co(1)O6 octahedra, and edges with three equivalent Co(2)O6 octahedra. All Ca(3)-O(3) bond lengths are 2.34 Å. All Ca(3)-O(4) bond lengths are 2.30 Å. In the fourth Ca site, Ca(4) is bonded to one O(5) and three equivalent O(7) atoms to form distorted CaO4 tetrahedra that share corners with three equivalent Co(2)O6 octahedra, corners with three equivalent Co(3)O6 octahedra, and corners with six equivalent Co(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-68°. The Ca(4)-O(5) bond length is 2.21 Å. All Ca(4)-O(7) bond lengths are 2.17 Å. In the fifth Ca site, Ca(5) is bonded to three equivalent O(1) and three equivalent O(11) atoms to form CaO6 octahedra that share corners with three equivalent Ca(1)O4 tetrahedra, corners with three equivalent Co(6)O4 tetrahedra, edges with three equivalent Co(1)O6 octahedra, and edges with three equivalent Co(5)O6 octahedra. All Ca(5)-O(1) bond lengths are 2.26 Å. All Ca(5)-O(11) bond lengths are 2.34 Å. In the sixth Ca site, Ca(6) is bonded to one O(12) and three equivalent O(8) atoms to form CaO4 tetrahedra that share corners with three equivalent Co(3)O6 octahedra, corners with three equivalent Co(5)O6 octahedra, and corners with six equivalent Co(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-65°. The Ca(6)-O(12) bond length is 2.20 Å. All Ca(6)-O(8) bond lengths are 2.20 Å. There are six inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form CoO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Co(6)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Co(4)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Co(1)O6 octahedra. The Co(1)-O(2) bond length is 2.06 Å. The Co(1)-O(6) bond length is 2.18 Å. Both Co(1)-O(1) bond lengths are 1.95 Å. Both Co(1)-O(4) bond lengths are 2.06 Å. In the second Co site, Co(2) is bonded to one O(10), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form CoO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Co(4)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 Co(3)O6 octahedra, and edges with four equivalent Co(2)O6 octahedra. The Co(2)-O(10) bond length is 2.20 Å. The Co(2)-O(5) bond length is 2.09 Å. Both Co(2)-O(3) bond lengths are 1.95 Å. Both Co(2)-O(8) bond lengths are 2.02 Å. In the third Co site, Co(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form CoO6 octahedra that share corners with three equivalent Ca(4)O4 tetrahedra, corners with three equivalent Ca(6)O4 tetrahedra, edges with three equivalent Co(2)O6 octahedra, and edges with three equivalent Co(5)O6 octahedra. All Co(3)-O(7) bond lengths are 1.91 Å. All Co(3)-O(8) bond lengths are 1.93 Å. In the fourth Co site, Co(4) is bonded to one O(10) and three equivalent O(4) atoms to form CoO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Co(2)O6 octahedra, and corners with six equivalent Co(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 54-63°. The Co(4)-O(10) bond length is 2.14 Å. All Co(4)-O(4) bond lengths are 2.01 Å. In the fifth Co site, Co(5) is bonded to one O(12), one O(9), two equivalent O(11), and two equivalent O(7) atoms to form CoO6 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 Co(6)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Co(3)O6 octahedra, and edges with four equivalent Co(5)O6 octahedra. The Co(5)-O(12) bond length is 2.04 Å. The Co(5)-O(9) bond length is 2.05 Å. Both Co(5)-O(11) bond lengths are 2.05 Å. Both Co(5)-O(7) bond lengths are 2.02 Å. In the sixth Co site, Co(6) is bonded to one O(6) and three equivalent O(11) atoms to form CoO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Co(1)O6 octahedra, and corners with six equivalent Co(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 53-67°. The Co(6)-O(6) bond length is 2.04 Å. All Co(6)-O(11) bond lengths are 2.01 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Ca(1), one Ca(5), and two equivalent Co(1) atoms to form distorted OCa2Co2 trigonal pyramids that share  a cornercorner with one O(9)CaCo3 trigonal pyramid, corners with two equivalent O(1)Ca2Co2 trigonal pyramids, corners with four equivalent O(4)CaCo3 trigonal pyramids,  an edgeedge with one O(2)CaCo3 trigonal pyramid, and edges with two equivalent O(1)Ca2Co2 trigonal pyramids. In the second O site, O(2) is bonded to one Ca(2) and three equivalent Co(1) atoms to form distorted OCaCo3 trigonal pyramids that share corners with three equivalent O(3)Ca2Co2 trigonal pyramids, corners with six equivalent O(4)CaCo3 trigonal pyramids, and edges with three equivalent O(1)Ca2Co2 trigonal pyramids. In the third O site, O(3) is bonded to one Ca(2), one Ca(3), and two equivalent Co(2) atoms to form OCa2Co2 trigonal pyramids that share corners with four equivalent O(8)CaCo3 tetrahedra,  a cornercorner with one O(2)CaCo3 trigonal pyramid, corners with two equivalent O(3)Ca2Co2 trigonal pyramids, corners with three equivalent O(4)CaCo3 trigonal pyramids,  an edgeedge with one O(5)CaCo3 trigonal pyramid, and edges with two equivalent O(3)Ca2Co2 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ca(3), one Co(4), and two equivalent Co(1) atoms to form distorted OCaCo3 trigonal pyramids that share corners with two equivalent O(2)CaCo3 trigonal pyramids, corners with two equivalent O(4)CaCo3 trigonal pyramids, corners with three equivalent O(3)Ca2Co2 trigonal pyramids, corners with four equivalent O(1)Ca2Co2 trigonal pyramids, and edges with two equivalent O(4)CaCo3 trigonal pyramids. In the fifth O site, O(5) is bonded to one Ca(4) and three equivalent Co(2) atoms to form distorted OCaCo3 trigonal pyramids that share corners with three equivalent O(7)CaCo3 tetrahedra, corners with six equivalent O(8)CaCo3 tetrahedra, and edges with three equivalent O(3)Ca2Co2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Co(6) and three equivalent Co(1) atoms. In the seventh O site, O(7) is bonded to one Ca(4), one Co(3), and two equivalent Co(5) atoms to form a mixture of corner and edge-sharing OCaCo3 tetrahedra. In the eighth O site, O(8) is bonded to one Ca(6), one Co(3), and two equivalent Co(2) atoms to form OCaCo3 tetrahedra that share  a cornercorner with one O(12)CaCo3 tetrahedra, corners with two equivalent O(8)CaCo3 tetrahedra, corners with three equivalent O(7)CaCo3 tetrahedra, corners with two equivalent O(5)CaCo3 trigonal pyramids, corners with four equivalent O(3)Ca2Co2 trigonal pyramids, and edges with two equivalent O(8)CaCo3 tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1) and three equivalent Co(5) atoms to form distorted OCaCo3 trigonal pyramids that share corners with three equivalent O(12)CaCo3 tetrahedra, corners with three equivalent O(1)Ca2Co2 trigonal pyramids, and edges with three equivalent O(7)CaCo3 tetrahedra. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Co(4) and three equivalent Co(2) atoms. In the eleventh O site, O(11) is bonded in a distorted rectangular see-saw-like geometry to one Ca(5), one Co(6), and two equivalent Co(5) atoms. In the twelfth O site, O(12) is bonded to one Ca(6) and three equivalent Co(5) atoms to form corner-sharing OCaCo3 tetrahedra.