CaTi2O4 crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with four equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(3) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form TiO6 octahedra that share corners with three equivalent Ca(1)O6 pentagonal pyramids, edges with two equivalent Ti(1)O6 octahedra, edges with four equivalent Ti(2)O6 octahedra, and  an edgeedge with one Ca(1)O6 pentagonal pyramid. In the second Ti site, Ti(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TiO6 octahedra that share edges with two equivalent Ti(2)O6 octahedra, edges with four equivalent Ti(1)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Ca(1), one Ti(1), and two equivalent Ti(2) atoms. In the second O site, O(2) is bonded to one Ca(2), one Ti(1), and two equivalent Ti(2) atoms to form OCaTi3 trigonal pyramids that share corners with four equivalent O(3)Ca2Ti3 trigonal bipyramids, corners with three equivalent O(2)CaTi3 trigonal pyramids, and edges with four equivalent O(3)Ca2Ti3 trigonal bipyramids. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), one Ti(2), and two equivalent Ti(1) atoms to form OCa2Ti3 trigonal bipyramids that share corners with five equivalent O(3)Ca2Ti3 trigonal bipyramids, corners with two equivalent O(2)CaTi3 trigonal pyramids, edges with four equivalent O(3)Ca2Ti3 trigonal bipyramids, and edges with two equivalent O(2)CaTi3 trigonal pyramids.
CaTi2O4 crystallizes in the orthorhombic Pmmn space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with six equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with four equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. Both Ca(1)-O(1) bond lengths are 2.28 Å. All Ca(1)-O(3) bond lengths are 2.40 Å. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(3) atoms. Both Ca(2)-O(2) bond lengths are 2.34 Å. All Ca(2)-O(3) bond lengths are 2.42 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form TiO6 octahedra that share corners with three equivalent Ca(1)O6 pentagonal pyramids, edges with two equivalent Ti(1)O6 octahedra, edges with four equivalent Ti(2)O6 octahedra, and  an edgeedge with one Ca(1)O6 pentagonal pyramid. The Ti(1)-O(1) bond length is 1.97 Å. The Ti(1)-O(2) bond length is 2.14 Å. All Ti(1)-O(3) bond lengths are 2.09 Å. In the second Ti site, Ti(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TiO6 octahedra that share edges with two equivalent Ti(2)O6 octahedra, edges with four equivalent Ti(1)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. Both Ti(2)-O(1) bond lengths are 2.08 Å. Both Ti(2)-O(2) bond lengths are 2.01 Å. Both Ti(2)-O(3) bond lengths are 2.12 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a rectangular see-saw-like geometry to one Ca(1), one Ti(1), and two equivalent Ti(2) atoms. In the second O site, O(2) is bonded to one Ca(2), one Ti(1), and two equivalent Ti(2) atoms to form OCaTi3 trigonal pyramids that share corners with four equivalent O(3)Ca2Ti3 trigonal bipyramids, corners with three equivalent O(2)CaTi3 trigonal pyramids, and edges with four equivalent O(3)Ca2Ti3 trigonal bipyramids. In the third O site, O(3) is bonded to one Ca(1), one Ca(2), one Ti(2), and two equivalent Ti(1) atoms to form OCa2Ti3 trigonal bipyramids that share corners with five equivalent O(3)Ca2Ti3 trigonal bipyramids, corners with two equivalent O(2)CaTi3 trigonal pyramids, edges with four equivalent O(3)Ca2Ti3 trigonal bipyramids, and edges with two equivalent O(2)CaTi3 trigonal pyramids.