Ca2Ti2O5 crystallizes in the orthorhombic Pbam space group. Ca(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Ti(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing TiO5 square pyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Ti(1) atoms to form distorted OCa4Ti2 octahedra that share corners with eight equivalent O(3)Ca4Ti2 octahedra, corners with eight equivalent O(2)Ca2Ti2 tetrahedra, edges with two equivalent O(1)Ca4Ti2 octahedra, edges with two equivalent O(2)Ca2Ti2 tetrahedra, and faces with four equivalent O(3)Ca4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 62-64°. In the second O site, O(2) is bonded to two equivalent Ca(1) and two equivalent Ti(1) atoms to form distorted OCa2Ti2 tetrahedra that share corners with four equivalent O(1)Ca4Ti2 octahedra, corners with four equivalent O(3)Ca4Ti2 octahedra, corners with four equivalent O(2)Ca2Ti2 tetrahedra,  an edgeedge with one O(1)Ca4Ti2 octahedra, and edges with four equivalent O(3)Ca4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 8-76°. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Ti(1) atoms to form distorted OCa4Ti2 octahedra that share corners with four equivalent O(1)Ca4Ti2 octahedra, corners with six equivalent O(3)Ca4Ti2 octahedra, corners with four equivalent O(2)Ca2Ti2 tetrahedra, edges with four equivalent O(3)Ca4Ti2 octahedra, edges with four equivalent O(2)Ca2Ti2 tetrahedra, and faces with two equivalent O(1)Ca4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 2-64°.
Ca2Ti2O5 crystallizes in the orthorhombic Pbam space group. Ca(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1), two equivalent O(2), and four equivalent O(3) atoms. Both Ca(1)-O(1) bond lengths are 2.64 Å. Both Ca(1)-O(2) bond lengths are 2.37 Å. There are a spread of Ca(1)-O(3) bond distances ranging from 2.45-2.87 Å. Ti(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing TiO5 square pyramids. The Ti(1)-O(1) bond length is 2.00 Å. There is one shorter (1.92 Å) and one longer (1.98 Å) Ti(1)-O(2) bond length. Both Ti(1)-O(3) bond lengths are 1.98 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Ti(1) atoms to form distorted OCa4Ti2 octahedra that share corners with eight equivalent O(3)Ca4Ti2 octahedra, corners with eight equivalent O(2)Ca2Ti2 tetrahedra, edges with two equivalent O(1)Ca4Ti2 octahedra, edges with two equivalent O(2)Ca2Ti2 tetrahedra, and faces with four equivalent O(3)Ca4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 62-64°. In the second O site, O(2) is bonded to two equivalent Ca(1) and two equivalent Ti(1) atoms to form distorted OCa2Ti2 tetrahedra that share corners with four equivalent O(1)Ca4Ti2 octahedra, corners with four equivalent O(3)Ca4Ti2 octahedra, corners with four equivalent O(2)Ca2Ti2 tetrahedra,  an edgeedge with one O(1)Ca4Ti2 octahedra, and edges with four equivalent O(3)Ca4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 8-76°. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Ti(1) atoms to form distorted OCa4Ti2 octahedra that share corners with four equivalent O(1)Ca4Ti2 octahedra, corners with six equivalent O(3)Ca4Ti2 octahedra, corners with four equivalent O(2)Ca2Ti2 tetrahedra, edges with four equivalent O(3)Ca4Ti2 octahedra, edges with four equivalent O(2)Ca2Ti2 tetrahedra, and faces with two equivalent O(1)Ca4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 2-64°.