Na2Ti2O5 crystallizes in the orthorhombic Pbcn space group. Na(1) is bonded to one O(3) and three equivalent O(2) atoms to form NaO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra, corners with five equivalent Ti(1)O4 tetrahedra, and  an edgeedge with one Na(1)O4 tetrahedra. Ti(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with three equivalent Ti(1)O4 tetrahedra and corners with five equivalent Na(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to three equivalent Na(1) and one Ti(1) atom to form a mixture of distorted corner and edge-sharing ONa3Ti trigonal pyramids. In the third O site, O(3) is bonded in a trigonal planar geometry to one Na(1) and two equivalent Ti(1) atoms.
Na2Ti2O5 crystallizes in the orthorhombic Pbcn space group. Na(1) is bonded to one O(3) and three equivalent O(2) atoms to form NaO4 tetrahedra that share corners with four equivalent Na(1)O4 tetrahedra, corners with five equivalent Ti(1)O4 tetrahedra, and  an edgeedge with one Na(1)O4 tetrahedra. The Na(1)-O(3) bond length is 2.30 Å. There are a spread of Na(1)-O(2) bond distances ranging from 2.27-2.34 Å. Ti(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form TiO4 tetrahedra that share corners with three equivalent Ti(1)O4 tetrahedra and corners with five equivalent Na(1)O4 tetrahedra. The Ti(1)-O(1) bond length is 1.83 Å. The Ti(1)-O(2) bond length is 1.75 Å. Both Ti(1)-O(3) bond lengths are 1.86 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Ti(1) atoms. In the second O site, O(2) is bonded to three equivalent Na(1) and one Ti(1) atom to form a mixture of distorted corner and edge-sharing ONa3Ti trigonal pyramids. In the third O site, O(3) is bonded in a trigonal planar geometry to one Na(1) and two equivalent Ti(1) atoms.