Na2Ti2O5 crystallizes in the orthorhombic Pca2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), and two equivalent O(1) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing TiO4 tetrahedra. In the second Ti site, Ti(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form corner-sharing TiO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Na(1), one Na(2), one Ti(1), and one Ti(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Ti(1), and one Ti(2) atom.
Na2Ti2O5 crystallizes in the orthorhombic Pca2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The Na(1)-O(3) bond length is 2.94 Å. The Na(1)-O(4) bond length is 2.47 Å. There is one shorter (2.65 Å) and one longer (2.83 Å) Na(1)-O(1) bond length. There is one shorter (2.48 Å) and one longer (2.52 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded in a 5-coordinate geometry to one O(2), one O(3), one O(5), and two equivalent O(1) atoms. The Na(2)-O(2) bond length is 2.44 Å. The Na(2)-O(3) bond length is 2.76 Å. The Na(2)-O(5) bond length is 2.69 Å. There is one shorter (2.41 Å) and one longer (2.55 Å) Na(2)-O(1) bond length. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form corner-sharing TiO4 tetrahedra. The Ti(1)-O(1) bond length is 1.76 Å. The Ti(1)-O(3) bond length is 1.86 Å. The Ti(1)-O(4) bond length is 1.87 Å. The Ti(1)-O(5) bond length is 1.85 Å. In the second Ti site, Ti(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form corner-sharing TiO4 tetrahedra. The Ti(2)-O(2) bond length is 1.76 Å. The Ti(2)-O(3) bond length is 1.86 Å. The Ti(2)-O(4) bond length is 1.86 Å. The Ti(2)-O(5) bond length is 1.86 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one Ti(2) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Na(1), one Na(2), one Ti(1), and one Ti(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Ti(1), and one Ti(2) atom.