La5Ti4O15 crystallizes in the trigonal P-3c1 space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. In the second La site, La(2) is bonded to three equivalent O(1), three equivalent O(3), and six equivalent O(2) atoms to form distorted LaO12 cuboctahedra that share corners with nine equivalent La(2)O12 cuboctahedra, faces with three equivalent La(3)O12 cuboctahedra, faces with three equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. In the third La site, La(3) is bonded to six equivalent O(2) and six equivalent O(3) atoms to form LaO12 cuboctahedra that share corners with six equivalent La(3)O12 cuboctahedra, faces with six equivalent La(2)O12 cuboctahedra, faces with two equivalent Ti(1)O6 octahedra, and faces with six equivalent Ti(2)O6 octahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form TiO6 octahedra that share corners with three equivalent Ti(2)O6 octahedra,  a faceface with one La(3)O12 cuboctahedra, and faces with three equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 14°. In the second Ti site, Ti(2) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form TiO6 octahedra that share corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, faces with three equivalent La(3)O12 cuboctahedra, and faces with four equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-14°. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted linear geometry to two equivalent La(2), two equivalent La(3), and two equivalent Ti(2) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Ti(1) atom. In the third O site, O(2) is bonded in a 2-coordinate geometry to one La(3), two equivalent La(2), one Ti(1), and one Ti(2) atom.
La5Ti4O15 crystallizes in the trigonal P-3c1 space group. There are three inequivalent La sites. In the first La site, La(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. There are three shorter (2.51 Å) and three longer (2.55 Å) La(1)-O(1) bond lengths. In the second La site, La(2) is bonded to three equivalent O(1), three equivalent O(3), and six equivalent O(2) atoms to form distorted LaO12 cuboctahedra that share corners with nine equivalent La(2)O12 cuboctahedra, faces with three equivalent La(3)O12 cuboctahedra, faces with three equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. All La(2)-O(1) bond lengths are 2.52 Å. All La(2)-O(3) bond lengths are 2.93 Å. There are three shorter (2.56 Å) and three longer (3.01 Å) La(2)-O(2) bond lengths. In the third La site, La(3) is bonded to six equivalent O(2) and six equivalent O(3) atoms to form LaO12 cuboctahedra that share corners with six equivalent La(3)O12 cuboctahedra, faces with six equivalent La(2)O12 cuboctahedra, faces with two equivalent Ti(1)O6 octahedra, and faces with six equivalent Ti(2)O6 octahedra. All La(3)-O(2) bond lengths are 2.74 Å. All La(3)-O(3) bond lengths are 2.78 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form TiO6 octahedra that share corners with three equivalent Ti(2)O6 octahedra,  a faceface with one La(3)O12 cuboctahedra, and faces with three equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 14°. All Ti(1)-O(1) bond lengths are 1.90 Å. All Ti(1)-O(2) bond lengths are 2.06 Å. In the second Ti site, Ti(2) is bonded to three equivalent O(2) and three equivalent O(3) atoms to form TiO6 octahedra that share corners with three equivalent Ti(1)O6 octahedra, corners with three equivalent Ti(2)O6 octahedra, faces with three equivalent La(3)O12 cuboctahedra, and faces with four equivalent La(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-14°. All Ti(2)-O(2) bond lengths are 1.98 Å. All Ti(2)-O(3) bond lengths are 1.97 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted linear geometry to two equivalent La(2), two equivalent La(3), and two equivalent Ti(2) atoms. In the second O site, O(1) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Ti(1) atom. In the third O site, O(2) is bonded in a 2-coordinate geometry to one La(3), two equivalent La(2), one Ti(1), and one Ti(2) atom.