Sr3TiNb4O15 crystallizes in the monoclinic Pc space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(1), one O(2), one O(7), one O(8), two equivalent O(10), two equivalent O(3), two equivalent O(4), and two equivalent O(9) atoms to form SrO12 cuboctahedra that share faces with two equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Ti(1)O6 octahedra, faces with two equivalent Nb(1)O6 octahedra, faces with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Nb(3)O6 octahedra. In the second Sr site, Sr(2) is bonded in a 11-coordinate geometry to one O(15), one O(2), one O(8), two equivalent O(10), two equivalent O(12), two equivalent O(13), and two equivalent O(5) atoms. In the third Sr site, Sr(3) is bonded in a 9-coordinate geometry to one O(1), one O(15), one O(7), two equivalent O(11), two equivalent O(14), and two equivalent O(9) atoms. Ti(1) is bonded to one O(11), one O(13), one O(3), one O(9), and two equivalent O(1) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 10-43°. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(10), one O(12), one O(14), one O(4), and two equivalent O(2) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-44°. In the second Nb site, Nb(2) is bonded to one O(14), one O(4), one O(6), one O(9), and two equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 13-44°. In the third Nb site, Nb(3) is bonded to one O(10), one O(13), one O(3), one O(5), and two equivalent O(8) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-43°. In the fourth Nb site, Nb(4) is bonded to one O(11), one O(12), one O(5), one O(6), and two equivalent O(15) atoms to form NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and corners with two equivalent Nb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-43°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(3), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(1), one Ti(1), and one Nb(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(2), one Nb(3), and one Nb(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(4) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(3), and two equivalent Nb(2) atoms. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Nb(3) atoms. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), one Ti(1), and one Nb(2) atom. In the tenth O site, O(10) is bonded in a distorted linear geometry to two equivalent Sr(1), two equivalent Sr(2), one Nb(1), and one Nb(3) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to two equivalent Sr(3), one Ti(1), and one Nb(4) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Nb(1), and one Nb(4) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(2), one Ti(1), and one Nb(3) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to two equivalent Sr(3), one Nb(1), and one Nb(2) atom. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Sr(2), one Sr(3), and two equivalent Nb(4) atoms.
Sr3TiNb4O15 crystallizes in the monoclinic Pc space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(1), one O(2), one O(7), one O(8), two equivalent O(10), two equivalent O(3), two equivalent O(4), and two equivalent O(9) atoms to form SrO12 cuboctahedra that share faces with two equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Ti(1)O6 octahedra, faces with two equivalent Nb(1)O6 octahedra, faces with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Nb(3)O6 octahedra. The Sr(1)-O(1) bond length is 2.69 Å. The Sr(1)-O(2) bond length is 2.71 Å. The Sr(1)-O(7) bond length is 2.83 Å. The Sr(1)-O(8) bond length is 2.74 Å. There is one shorter (2.78 Å) and one longer (2.84 Å) Sr(1)-O(10) bond length. There is one shorter (2.65 Å) and one longer (2.67 Å) Sr(1)-O(3) bond length. There is one shorter (2.69 Å) and one longer (2.71 Å) Sr(1)-O(4) bond length. There is one shorter (2.91 Å) and one longer (2.94 Å) Sr(1)-O(9) bond length. In the second Sr site, Sr(2) is bonded in a 11-coordinate geometry to one O(15), one O(2), one O(8), two equivalent O(10), two equivalent O(12), two equivalent O(13), and two equivalent O(5) atoms. The Sr(2)-O(15) bond length is 3.12 Å. The Sr(2)-O(2) bond length is 3.05 Å. The Sr(2)-O(8) bond length is 2.80 Å. Both Sr(2)-O(10) bond lengths are 3.00 Å. There is one shorter (2.67 Å) and one longer (2.78 Å) Sr(2)-O(12) bond length. There is one shorter (2.71 Å) and one longer (2.74 Å) Sr(2)-O(13) bond length. There is one shorter (3.08 Å) and one longer (3.09 Å) Sr(2)-O(5) bond length. In the third Sr site, Sr(3) is bonded in a 9-coordinate geometry to one O(1), one O(15), one O(7), two equivalent O(11), two equivalent O(14), and two equivalent O(9) atoms. The Sr(3)-O(1) bond length is 2.61 Å. The Sr(3)-O(15) bond length is 3.13 Å. The Sr(3)-O(7) bond length is 2.65 Å. There is one shorter (2.57 Å) and one longer (2.69 Å) Sr(3)-O(11) bond length. There is one shorter (2.87 Å) and one longer (2.97 Å) Sr(3)-O(14) bond length. There is one shorter (2.61 Å) and one longer (2.73 Å) Sr(3)-O(9) bond length. Ti(1) is bonded to one O(11), one O(13), one O(3), one O(9), and two equivalent O(1) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 10-43°. The Ti(1)-O(11) bond length is 2.06 Å. The Ti(1)-O(13) bond length is 1.95 Å. The Ti(1)-O(3) bond length is 1.91 Å. The Ti(1)-O(9) bond length is 2.09 Å. There is one shorter (1.80 Å) and one longer (2.22 Å) Ti(1)-O(1) bond length. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(10), one O(12), one O(14), one O(4), and two equivalent O(2) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(3)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-44°. The Nb(1)-O(10) bond length is 2.13 Å. The Nb(1)-O(12) bond length is 1.94 Å. The Nb(1)-O(14) bond length is 1.92 Å. The Nb(1)-O(4) bond length is 2.08 Å. There is one shorter (1.97 Å) and one longer (2.07 Å) Nb(1)-O(2) bond length. In the second Nb site, Nb(2) is bonded to one O(14), one O(4), one O(6), one O(9), and two equivalent O(7) atoms to form NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 13-44°. The Nb(2)-O(14) bond length is 2.15 Å. The Nb(2)-O(4) bond length is 1.94 Å. The Nb(2)-O(6) bond length is 1.95 Å. The Nb(2)-O(9) bond length is 2.02 Å. There is one shorter (1.93 Å) and one longer (2.10 Å) Nb(2)-O(7) bond length. In the third Nb site, Nb(3) is bonded to one O(10), one O(13), one O(3), one O(5), and two equivalent O(8) atoms to form NbO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(4)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-43°. The Nb(3)-O(10) bond length is 2.01 Å. The Nb(3)-O(13) bond length is 2.05 Å. The Nb(3)-O(3) bond length is 2.04 Å. The Nb(3)-O(5) bond length is 1.96 Å. There is one shorter (1.94 Å) and one longer (2.08 Å) Nb(3)-O(8) bond length. In the fourth Nb site, Nb(4) is bonded to one O(11), one O(12), one O(5), one O(6), and two equivalent O(15) atoms to form NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Nb(1)O6 octahedra,  a cornercorner with one Nb(2)O6 octahedra,  a cornercorner with one Nb(3)O6 octahedra, and corners with two equivalent Nb(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-43°. The Nb(4)-O(11) bond length is 1.91 Å. The Nb(4)-O(12) bond length is 2.12 Å. The Nb(4)-O(5) bond length is 2.03 Å. The Nb(4)-O(6) bond length is 2.00 Å. There is one shorter (1.87 Å) and one longer (2.15 Å) Nb(4)-O(15) bond length. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(3), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(1), one Ti(1), and one Nb(3) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(2), one Nb(3), and one Nb(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Nb(2) and one Nb(4) atom. In the seventh O site, O(7) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(3), and two equivalent Nb(2) atoms. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Nb(3) atoms. In the ninth O site, O(9) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), one Ti(1), and one Nb(2) atom. In the tenth O site, O(10) is bonded in a distorted linear geometry to two equivalent Sr(1), two equivalent Sr(2), one Nb(1), and one Nb(3) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to two equivalent Sr(3), one Ti(1), and one Nb(4) atom. In the twelfth O site, O(12) is bonded in a 4-coordinate geometry to two equivalent Sr(2), one Nb(1), and one Nb(4) atom. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(2), one Ti(1), and one Nb(3) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to two equivalent Sr(3), one Nb(1), and one Nb(2) atom. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Sr(2), one Sr(3), and two equivalent Nb(4) atoms.