CaTi2O4 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 Ti(5)O6 octahedra, and corners with six equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-70°. 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 Ti(1)O6 octahedra, and corners with six equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-73°. In the third Ca site, Ca(3) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Ti(4)O4 tetrahedra, edges with three equivalent Ti(1)O6 octahedra, and edges with three equivalent Ti(2)O6 octahedra. In the fourth Ca site, Ca(4) is bonded to one O(5) and three equivalent O(7) atoms to form CaO4 tetrahedra that share corners with three equivalent Ti(2)O6 octahedra, corners with three equivalent Ti(3)O6 octahedra, and corners with six equivalent Ti(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-62°. 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 Ti(6)O4 tetrahedra, edges with three equivalent Ti(1)O6 octahedra, and edges with three equivalent Ti(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 Ti(3)O6 octahedra, corners with three equivalent Ti(5)O6 octahedra, and corners with six equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-61°. There are six inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form TiO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Ti(6)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Ti(4)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Ti(1)O6 octahedra. In the second Ti site, Ti(2) is bonded to one O(10), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form TiO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Ti(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 Ti(3)O6 octahedra, and edges with four equivalent Ti(2)O6 octahedra. In the third Ti site, Ti(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form TiO6 octahedra that share corners with three equivalent Ca(4)O4 tetrahedra, corners with three equivalent Ca(6)O4 tetrahedra, edges with three equivalent Ti(2)O6 octahedra, and edges with three equivalent Ti(5)O6 octahedra. In the fourth Ti site, Ti(4) is bonded to one O(10) and three equivalent O(4) atoms to form TiO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, and corners with six equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-60°. In the fifth Ti site, Ti(5) is bonded to one O(12), one O(9), two equivalent O(11), and two equivalent O(7) atoms to form TiO6 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 Ti(6)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, and edges with four equivalent Ti(5)O6 octahedra. In the sixth Ti site, Ti(6) is bonded to one O(6) and three equivalent O(11) atoms to form TiO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, and corners with six equivalent Ti(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. 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 Ti(1) atoms to form distorted OCa2Ti2 trigonal pyramids that share  a cornercorner with one O(9)CaTi3 trigonal pyramid, corners with two equivalent O(1)Ca2Ti2 trigonal pyramids,  an edgeedge with one O(2)CaTi3 tetrahedra, and edges with two equivalent O(1)Ca2Ti2 trigonal pyramids. In the second O site, O(2) is bonded to one Ca(2) and three equivalent Ti(1) atoms to form a mixture of distorted edge and corner-sharing OCaTi3 tetrahedra. In the third O site, O(3) is bonded to one Ca(2), one Ca(3), and two equivalent Ti(2) atoms to form OCa2Ti2 trigonal pyramids that share  a cornercorner with one O(2)CaTi3 tetrahedra, corners with four equivalent O(8)CaTi3 tetrahedra, corners with two equivalent O(3)Ca2Ti2 trigonal pyramids,  an edgeedge with one O(5)CaTi3 tetrahedra, and edges with two equivalent O(3)Ca2Ti2 trigonal pyramids. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Ca(3), one Ti(4), and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded to one Ca(4) and three equivalent Ti(2) atoms to form distorted OCaTi3 tetrahedra that share corners with three equivalent O(7)CaTi3 tetrahedra, corners with six equivalent O(8)CaTi3 tetrahedra, and edges with three equivalent O(3)Ca2Ti2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Ti(6) and three equivalent Ti(1) atoms. In the seventh O site, O(7) is bonded to one Ca(4), one Ti(3), and two equivalent Ti(5) atoms to form a mixture of distorted edge and corner-sharing OCaTi3 tetrahedra. In the eighth O site, O(8) is bonded to one Ca(6), one Ti(3), and two equivalent Ti(2) atoms to form distorted OCaTi3 tetrahedra that share  a cornercorner with one O(12)CaTi3 tetrahedra, corners with two equivalent O(5)CaTi3 tetrahedra, corners with two equivalent O(8)CaTi3 tetrahedra, corners with three equivalent O(7)CaTi3 tetrahedra, corners with four equivalent O(3)Ca2Ti2 trigonal pyramids, and edges with two equivalent O(8)CaTi3 tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1) and three equivalent Ti(5) atoms to form distorted OCaTi3 trigonal pyramids that share corners with three equivalent O(12)CaTi3 tetrahedra, corners with three equivalent O(1)Ca2Ti2 trigonal pyramids, and edges with three equivalent O(7)CaTi3 tetrahedra. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Ti(4) and three equivalent Ti(2) atoms. In the eleventh O site, O(11) is bonded in a rectangular see-saw-like geometry to one Ca(5), one Ti(6), and two equivalent Ti(5) atoms. In the twelfth O site, O(12) is bonded to one Ca(6) and three equivalent Ti(5) atoms to form distorted corner-sharing OCaTi3 tetrahedra.
CaTi2O4 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 Ti(5)O6 octahedra, and corners with six equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-70°. The Ca(1)-O(9) bond length is 2.28 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 Ti(1)O6 octahedra, and corners with six equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-73°. The Ca(2)-O(2) bond length is 2.22 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 CaO6 octahedra that share corners with three equivalent Ca(2)O4 tetrahedra, corners with three equivalent Ti(4)O4 tetrahedra, edges with three equivalent Ti(1)O6 octahedra, and edges with three equivalent Ti(2)O6 octahedra. All Ca(3)-O(3) bond lengths are 2.30 Å. All Ca(3)-O(4) bond lengths are 2.33 Å. In the fourth Ca site, Ca(4) is bonded to one O(5) and three equivalent O(7) atoms to form CaO4 tetrahedra that share corners with three equivalent Ti(2)O6 octahedra, corners with three equivalent Ti(3)O6 octahedra, and corners with six equivalent Ti(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-62°. The Ca(4)-O(5) bond length is 2.17 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 Ti(6)O4 tetrahedra, edges with three equivalent Ti(1)O6 octahedra, and edges with three equivalent Ti(5)O6 octahedra. All Ca(5)-O(1) bond lengths are 2.25 Å. All Ca(5)-O(11) bond lengths are 2.36 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 Ti(3)O6 octahedra, corners with three equivalent Ti(5)O6 octahedra, and corners with six equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 60-61°. The Ca(6)-O(12) bond length is 2.22 Å. All Ca(6)-O(8) bond lengths are 2.17 Å. There are six inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(6), two equivalent O(1), and two equivalent O(4) atoms to form TiO6 octahedra that share  a cornercorner with one Ca(2)O4 tetrahedra,  a cornercorner with one Ti(6)O4 tetrahedra, corners with two equivalent Ca(1)O4 tetrahedra, corners with two equivalent Ti(4)O4 tetrahedra,  an edgeedge with one Ca(3)O6 octahedra,  an edgeedge with one Ca(5)O6 octahedra, and edges with four equivalent Ti(1)O6 octahedra. The Ti(1)-O(2) bond length is 2.13 Å. The Ti(1)-O(6) bond length is 2.24 Å. Both Ti(1)-O(1) bond lengths are 2.02 Å. Both Ti(1)-O(4) bond lengths are 2.16 Å. In the second Ti site, Ti(2) is bonded to one O(10), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form TiO6 octahedra that share  a cornercorner with one Ca(4)O4 tetrahedra,  a cornercorner with one Ti(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 Ti(3)O6 octahedra, and edges with four equivalent Ti(2)O6 octahedra. The Ti(2)-O(10) bond length is 2.22 Å. The Ti(2)-O(5) bond length is 2.12 Å. Both Ti(2)-O(3) bond lengths are 2.01 Å. Both Ti(2)-O(8) bond lengths are 2.06 Å. In the third Ti site, Ti(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form TiO6 octahedra that share corners with three equivalent Ca(4)O4 tetrahedra, corners with three equivalent Ca(6)O4 tetrahedra, edges with three equivalent Ti(2)O6 octahedra, and edges with three equivalent Ti(5)O6 octahedra. All Ti(3)-O(7) bond lengths are 2.04 Å. All Ti(3)-O(8) bond lengths are 2.04 Å. In the fourth Ti site, Ti(4) is bonded to one O(10) and three equivalent O(4) atoms to form TiO4 tetrahedra that share corners with three equivalent Ca(3)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, and corners with six equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-60°. The Ti(4)-O(10) bond length is 2.01 Å. All Ti(4)-O(4) bond lengths are 1.89 Å. In the fifth Ti site, Ti(5) is bonded to one O(12), one O(9), two equivalent O(11), and two equivalent O(7) atoms to form TiO6 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 Ti(6)O4 tetrahedra,  an edgeedge with one Ca(5)O6 octahedra,  an edgeedge with one Ti(3)O6 octahedra, and edges with four equivalent Ti(5)O6 octahedra. The Ti(5)-O(12) bond length is 2.08 Å. The Ti(5)-O(9) bond length is 2.07 Å. Both Ti(5)-O(11) bond lengths are 2.17 Å. Both Ti(5)-O(7) bond lengths are 2.05 Å. In the sixth Ti site, Ti(6) is bonded to one O(6) and three equivalent O(11) atoms to form TiO4 tetrahedra that share corners with three equivalent Ca(5)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, and corners with six equivalent Ti(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-62°. The Ti(6)-O(6) bond length is 1.96 Å. All Ti(6)-O(11) bond lengths are 1.90 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 Ti(1) atoms to form distorted OCa2Ti2 trigonal pyramids that share  a cornercorner with one O(9)CaTi3 trigonal pyramid, corners with two equivalent O(1)Ca2Ti2 trigonal pyramids,  an edgeedge with one O(2)CaTi3 tetrahedra, and edges with two equivalent O(1)Ca2Ti2 trigonal pyramids. In the second O site, O(2) is bonded to one Ca(2) and three equivalent Ti(1) atoms to form a mixture of distorted edge and corner-sharing OCaTi3 tetrahedra. In the third O site, O(3) is bonded to one Ca(2), one Ca(3), and two equivalent Ti(2) atoms to form OCa2Ti2 trigonal pyramids that share  a cornercorner with one O(2)CaTi3 tetrahedra, corners with four equivalent O(8)CaTi3 tetrahedra, corners with two equivalent O(3)Ca2Ti2 trigonal pyramids,  an edgeedge with one O(5)CaTi3 tetrahedra, and edges with two equivalent O(3)Ca2Ti2 trigonal pyramids. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Ca(3), one Ti(4), and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded to one Ca(4) and three equivalent Ti(2) atoms to form distorted OCaTi3 tetrahedra that share corners with three equivalent O(7)CaTi3 tetrahedra, corners with six equivalent O(8)CaTi3 tetrahedra, and edges with three equivalent O(3)Ca2Ti2 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Ti(6) and three equivalent Ti(1) atoms. In the seventh O site, O(7) is bonded to one Ca(4), one Ti(3), and two equivalent Ti(5) atoms to form a mixture of distorted edge and corner-sharing OCaTi3 tetrahedra. In the eighth O site, O(8) is bonded to one Ca(6), one Ti(3), and two equivalent Ti(2) atoms to form distorted OCaTi3 tetrahedra that share  a cornercorner with one O(12)CaTi3 tetrahedra, corners with two equivalent O(5)CaTi3 tetrahedra, corners with two equivalent O(8)CaTi3 tetrahedra, corners with three equivalent O(7)CaTi3 tetrahedra, corners with four equivalent O(3)Ca2Ti2 trigonal pyramids, and edges with two equivalent O(8)CaTi3 tetrahedra. In the ninth O site, O(9) is bonded to one Ca(1) and three equivalent Ti(5) atoms to form distorted OCaTi3 trigonal pyramids that share corners with three equivalent O(12)CaTi3 tetrahedra, corners with three equivalent O(1)Ca2Ti2 trigonal pyramids, and edges with three equivalent O(7)CaTi3 tetrahedra. In the tenth O site, O(10) is bonded in a rectangular see-saw-like geometry to one Ti(4) and three equivalent Ti(2) atoms. In the eleventh O site, O(11) is bonded in a rectangular see-saw-like geometry to one Ca(5), one Ti(6), and two equivalent Ti(5) atoms. In the twelfth O site, O(12) is bonded to one Ca(6) and three equivalent Ti(5) atoms to form distorted corner-sharing OCaTi3 tetrahedra.