La2Ti3O9 crystallizes in the monoclinic P2_1 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom. In the second La site, La(2) is bonded in a 10-coordinate geometry to one O(4), one O(6), one O(7), one O(8), two equivalent O(2), two equivalent O(3), and two equivalent O(9) atoms. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form corner-sharing TiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-53°. In the second Ti site, Ti(2) is bonded to one O(4), one O(7), one O(8), and one O(9) atom to form corner-sharing TiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-68°. In the third Ti site, Ti(3) is bonded to one O(7), one O(8), two equivalent O(5), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O4 tetrahedra, corners with two equivalent Ti(2)O4 tetrahedra, and edges with two equivalent Ti(3)O6 octahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one La(1) and one Ti(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Ti(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to one La(2) and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Ti(3) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one La(2) and two equivalent Ti(3) atoms. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one La(1), one La(2), one Ti(2), and one Ti(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Ti(2), and one Ti(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one La(1), two equivalent La(2), and one Ti(2) atom.
La2Ti3O9 crystallizes in the monoclinic P2_1 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(7), one O(8), and one O(9) atom. The La(1)-O(1) bond length is 2.37 Å. The La(1)-O(2) bond length is 2.52 Å. The La(1)-O(3) bond length is 2.52 Å. The La(1)-O(7) bond length is 2.56 Å. The La(1)-O(8) bond length is 2.60 Å. The La(1)-O(9) bond length is 2.41 Å. In the second La site, La(2) is bonded in a 10-coordinate geometry to one O(4), one O(6), one O(7), one O(8), two equivalent O(2), two equivalent O(3), and two equivalent O(9) atoms. The La(2)-O(4) bond length is 2.30 Å. The La(2)-O(6) bond length is 2.55 Å. The La(2)-O(7) bond length is 3.02 Å. The La(2)-O(8) bond length is 2.98 Å. There is one shorter (2.46 Å) and one longer (2.88 Å) La(2)-O(2) bond length. There is one shorter (2.47 Å) and one longer (2.84 Å) La(2)-O(3) bond length. There is one shorter (3.16 Å) and one longer (3.21 Å) La(2)-O(9) bond length. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form corner-sharing TiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-53°. The Ti(1)-O(1) bond length is 1.76 Å. The Ti(1)-O(2) bond length is 1.84 Å. The Ti(1)-O(3) bond length is 1.84 Å. The Ti(1)-O(5) bond length is 1.91 Å. In the second Ti site, Ti(2) is bonded to one O(4), one O(7), one O(8), and one O(9) atom to form corner-sharing TiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 63-68°. The Ti(2)-O(4) bond length is 1.78 Å. The Ti(2)-O(7) bond length is 1.87 Å. The Ti(2)-O(8) bond length is 1.88 Å. The Ti(2)-O(9) bond length is 1.78 Å. In the third Ti site, Ti(3) is bonded to one O(7), one O(8), two equivalent O(5), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O4 tetrahedra, corners with two equivalent Ti(2)O4 tetrahedra, and edges with two equivalent Ti(3)O6 octahedra. The Ti(3)-O(7) bond length is 1.98 Å. The Ti(3)-O(8) bond length is 1.99 Å. There is one shorter (2.00 Å) and one longer (2.02 Å) Ti(3)-O(5) bond length. There is one shorter (1.79 Å) and one longer (2.20 Å) Ti(3)-O(6) bond length. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one La(1) and one Ti(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Ti(1) atom. In the fourth O site, O(4) is bonded in a linear geometry to one La(2) and one Ti(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ti(1) and two equivalent Ti(3) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one La(2) and two equivalent Ti(3) atoms. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one La(1), one La(2), one Ti(2), and one Ti(3) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Ti(2), and one Ti(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 120 degrees geometry to one La(1), two equivalent La(2), and one Ti(2) atom.