Sr2LaTi2Nb3O15 crystallizes in the orthorhombic Pbam space group. Sr(1) is bonded in a 9-coordinate geometry to one O(3), one O(4), one O(8), two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms. La(1) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form LaO12 cuboctahedra that share faces with two equivalent La(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Nb(1)O6 octahedra. Ti(1) is bonded to one O(1), one O(5), one O(6), one O(7), and two equivalent O(3) atoms to form TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 9-45°. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-45°. In the second Nb site, Nb(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, and corners with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-40°. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1), one Ti(1), and one Nb(1) atom. In the second O site, O(6) is bonded in a distorted linear geometry to two equivalent La(1), one Ti(1), and one Nb(1) atom. In the third O site, O(7) is bonded to two equivalent Sr(1), one Ti(1), and one Nb(1) atom to form distorted corner-sharing OSr2TiNb tetrahedra. In the fourth O site, O(8) is bonded in a linear geometry to two equivalent Sr(1) and two equivalent Nb(2) atoms. In the fifth O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Sr(1), one Ti(1), and one Nb(2) atom. In the sixth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(1), one Nb(1), and one Nb(2) atom. In the seventh O site, O(3) is bonded in a 2-coordinate geometry to one Sr(1), one La(1), and two equivalent Ti(1) atoms. In the eighth O site, O(4) is bonded in a distorted linear geometry to one Sr(1), one La(1), and two equivalent Nb(1) atoms.
Sr2LaTi2Nb3O15 crystallizes in the orthorhombic Pbam space group. Sr(1) is bonded in a 9-coordinate geometry to one O(3), one O(4), one O(8), two equivalent O(1), two equivalent O(2), and two equivalent O(7) atoms. The Sr(1)-O(3) bond length is 3.20 Å. The Sr(1)-O(4) bond length is 3.14 Å. The Sr(1)-O(8) bond length is 2.99 Å. Both Sr(1)-O(1) bond lengths are 2.83 Å. Both Sr(1)-O(2) bond lengths are 2.78 Å. Both Sr(1)-O(7) bond lengths are 2.69 Å. La(1) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form LaO12 cuboctahedra that share faces with two equivalent La(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Nb(1)O6 octahedra. Both La(1)-O(3) bond lengths are 2.64 Å. Both La(1)-O(4) bond lengths are 2.69 Å. All La(1)-O(5) bond lengths are 2.69 Å. All La(1)-O(6) bond lengths are 2.71 Å. Ti(1) is bonded to one O(1), one O(5), one O(6), one O(7), and two equivalent O(3) atoms to form TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with three equivalent Nb(1)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 9-45°. The Ti(1)-O(1) bond length is 1.92 Å. The Ti(1)-O(5) bond length is 1.98 Å. The Ti(1)-O(6) bond length is 2.01 Å. The Ti(1)-O(7) bond length is 2.01 Å. Both Ti(1)-O(3) bond lengths are 1.99 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(2), one O(5), one O(6), one O(7), and two equivalent O(4) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with three equivalent Ti(1)O6 octahedra, and faces with two equivalent La(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-45°. The Nb(1)-O(2) bond length is 1.98 Å. The Nb(1)-O(5) bond length is 2.03 Å. The Nb(1)-O(6) bond length is 1.98 Å. The Nb(1)-O(7) bond length is 2.00 Å. Both Nb(1)-O(4) bond lengths are 1.99 Å. In the second Nb site, Nb(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, and corners with two equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-40°. Both Nb(2)-O(1) bond lengths are 1.99 Å. Both Nb(2)-O(2) bond lengths are 2.02 Å. Both Nb(2)-O(8) bond lengths are 1.98 Å. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1), one Ti(1), and one Nb(1) atom. In the second O site, O(6) is bonded in a distorted linear geometry to two equivalent La(1), one Ti(1), and one Nb(1) atom. In the third O site, O(7) is bonded to two equivalent Sr(1), one Ti(1), and one Nb(1) atom to form distorted corner-sharing OSr2TiNb tetrahedra. In the fourth O site, O(8) is bonded in a linear geometry to two equivalent Sr(1) and two equivalent Nb(2) atoms. In the fifth O site, O(1) is bonded in a distorted bent 150 degrees geometry to two equivalent Sr(1), one Ti(1), and one Nb(2) atom. In the sixth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(1), one Nb(1), and one Nb(2) atom. In the seventh O site, O(3) is bonded in a 2-coordinate geometry to one Sr(1), one La(1), and two equivalent Ti(1) atoms. In the eighth O site, O(4) is bonded in a distorted linear geometry to one Sr(1), one La(1), and two equivalent Nb(1) atoms.