Ca2Ti3O8 is beta indium sulfide-derived structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with three equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 19-59°. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TiO6 octahedra that share corners with six equivalent Ca(1)O6 pentagonal pyramids, edges with four equivalent Ti(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. 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 corners with four equivalent Ca(1)O6 pentagonal pyramids, edges with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(2)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 distorted trigonal planar geometry to one Ca(1) and two equivalent Ti(2) atoms. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Ca(1), one Ti(1), and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1), one Ti(1), and one Ti(2) atom to form a mixture of distorted edge and corner-sharing OCa2Ti2 trigonal pyramids.
Ca2Ti3O8 is beta indium sulfide-derived structured and crystallizes in the monoclinic C2/m space group. Ca(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with three equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra,  an edgeedge with one Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 19-59°. The Ca(1)-O(1) bond length is 2.32 Å. The Ca(1)-O(2) bond length is 2.37 Å. There are two shorter (2.30 Å) and two longer (2.42 Å) Ca(1)-O(3) bond lengths. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form TiO6 octahedra that share corners with six equivalent Ca(1)O6 pentagonal pyramids, edges with four equivalent Ti(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. Both Ti(1)-O(2) bond lengths are 1.96 Å. All Ti(1)-O(3) bond lengths are 1.96 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 corners with four equivalent Ca(1)O6 pentagonal pyramids, edges with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(2)O6 octahedra, and edges with two equivalent Ca(1)O6 pentagonal pyramids. Both Ti(2)-O(1) bond lengths are 1.90 Å. Both Ti(2)-O(2) bond lengths are 2.11 Å. Both Ti(2)-O(3) bond lengths are 1.94 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Ti(2) atoms. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Ca(1), one Ti(1), and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded to two equivalent Ca(1), one Ti(1), and one Ti(2) atom to form a mixture of distorted edge and corner-sharing OCa2Ti2 trigonal pyramids.