Ba3TiNb4O15 crystallizes in the monoclinic Pc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(1), one O(2), one O(3), one O(4), two equivalent O(10), two equivalent O(11), two equivalent O(12), and two equivalent O(13) atoms to form BaO12 cuboctahedra that share faces with two equivalent Ba(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 Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(14), two equivalent O(6), and two equivalent O(9) atoms. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to two equivalent O(15), two equivalent O(7), and two equivalent O(8) atoms. Ti(1) is bonded to one O(10), one O(12), one O(14), one O(8), 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-40°. There are four inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(11), one O(13), one O(15), one O(9), 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-40°. In the second Nb site, Nb(2) is bonded to one O(11), one O(12), one O(15), one O(7), and two equivalent O(3) 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-40°. In the third Nb site, Nb(3) is bonded to one O(10), one O(13), one O(14), one O(6), and two equivalent O(4) 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-40°. In the fourth Nb site, Nb(4) is bonded to one O(6), one O(7), one O(8), one O(9), and two equivalent O(5) 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 4-38°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ba(1) and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Nb(2) atoms. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Nb(3) atoms. In the fifth O site, O(5) is bonded in a distorted linear geometry to two equivalent Nb(4) atoms. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Nb(3), and one Nb(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Nb(2), and one Nb(4) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Ti(1), and one Nb(4) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Nb(1), and one Nb(4) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Nb(3) atom. In the eleventh O site, O(11) is bonded in a distorted linear geometry to two equivalent Ba(1), one Nb(1), and one Nb(2) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Nb(2) atom. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Nb(1), and one Nb(3) atom. In the fourteenth O site, O(14) is bonded to two equivalent Ba(2), one Ti(1), and one Nb(3) atom to form distorted corner-sharing OBa2TiNb trigonal pyramids. In the fifteenth O site, O(15) is bonded to two equivalent Ba(3), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OBa2Nb2 trigonal pyramids.
Ba3TiNb4O15 crystallizes in the monoclinic Pc space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to one O(1), one O(2), one O(3), one O(4), two equivalent O(10), two equivalent O(11), two equivalent O(12), and two equivalent O(13) atoms to form BaO12 cuboctahedra that share faces with two equivalent Ba(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 Ba(1)-O(1) bond length is 2.74 Å. The Ba(1)-O(2) bond length is 2.86 Å. The Ba(1)-O(3) bond length is 2.85 Å. The Ba(1)-O(4) bond length is 2.80 Å. There is one shorter (2.76 Å) and one longer (2.90 Å) Ba(1)-O(10) bond length. There is one shorter (2.83 Å) and one longer (2.98 Å) Ba(1)-O(11) bond length. There is one shorter (2.80 Å) and one longer (2.92 Å) Ba(1)-O(12) bond length. There is one shorter (2.80 Å) and one longer (2.95 Å) Ba(1)-O(13) bond length. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(14), two equivalent O(6), and two equivalent O(9) atoms. There is one shorter (2.80 Å) and one longer (2.87 Å) Ba(2)-O(14) bond length. There is one shorter (2.89 Å) and one longer (2.94 Å) Ba(2)-O(6) bond length. There is one shorter (2.98 Å) and one longer (3.03 Å) Ba(2)-O(9) bond length. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to two equivalent O(15), two equivalent O(7), and two equivalent O(8) atoms. There is one shorter (2.85 Å) and one longer (2.90 Å) Ba(3)-O(15) bond length. There is one shorter (2.96 Å) and one longer (2.98 Å) Ba(3)-O(7) bond length. Both Ba(3)-O(8) bond lengths are 2.93 Å. Ti(1) is bonded to one O(10), one O(12), one O(14), one O(8), 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-40°. The Ti(1)-O(10) bond length is 1.99 Å. The Ti(1)-O(12) bond length is 2.15 Å. The Ti(1)-O(14) bond length is 1.98 Å. The Ti(1)-O(8) bond length is 1.97 Å. There is one shorter (1.76 Å) and one longer (2.36 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(11), one O(13), one O(15), one O(9), 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-40°. The Nb(1)-O(11) bond length is 2.08 Å. The Nb(1)-O(13) bond length is 2.06 Å. The Nb(1)-O(15) bond length is 2.01 Å. The Nb(1)-O(9) bond length is 1.93 Å. There is one shorter (1.88 Å) and one longer (2.26 Å) Nb(1)-O(2) bond length. In the second Nb site, Nb(2) is bonded to one O(11), one O(12), one O(15), one O(7), and two equivalent O(3) 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 2-40°. The Nb(2)-O(11) bond length is 2.01 Å. The Nb(2)-O(12) bond length is 1.95 Å. The Nb(2)-O(15) bond length is 2.06 Å. The Nb(2)-O(7) bond length is 2.04 Å. There is one shorter (1.89 Å) and one longer (2.23 Å) Nb(2)-O(3) bond length. In the third Nb site, Nb(3) is bonded to one O(10), one O(13), one O(14), one O(6), and two equivalent O(4) 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 Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-40°. The Nb(3)-O(10) bond length is 2.06 Å. The Nb(3)-O(13) bond length is 2.05 Å. The Nb(3)-O(14) bond length is 2.00 Å. The Nb(3)-O(6) bond length is 1.96 Å. There is one shorter (1.89 Å) and one longer (2.24 Å) Nb(3)-O(4) bond length. In the fourth Nb site, Nb(4) is bonded to one O(6), one O(7), one O(8), one O(9), and two equivalent O(5) 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 4-38°. The Nb(4)-O(6) bond length is 2.03 Å. The Nb(4)-O(7) bond length is 1.97 Å. The Nb(4)-O(8) bond length is 1.93 Å. The Nb(4)-O(9) bond length is 2.08 Å. There is one shorter (1.86 Å) and one longer (2.27 Å) Nb(4)-O(5) bond length. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ba(1) and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Nb(2) atoms. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Nb(3) atoms. In the fifth O site, O(5) is bonded in a distorted linear geometry to two equivalent Nb(4) atoms. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Nb(3), and one Nb(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Nb(2), and one Nb(4) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Ti(1), and one Nb(4) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Nb(1), and one Nb(4) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Nb(3) atom. In the eleventh O site, O(11) is bonded in a distorted linear geometry to two equivalent Ba(1), one Nb(1), and one Nb(2) atom. In the twelfth O site, O(12) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Nb(2) atom. In the thirteenth O site, O(13) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Nb(1), and one Nb(3) atom. In the fourteenth O site, O(14) is bonded to two equivalent Ba(2), one Ti(1), and one Nb(3) atom to form distorted corner-sharing OBa2TiNb trigonal pyramids. In the fifteenth O site, O(15) is bonded to two equivalent Ba(3), one Nb(1), and one Nb(2) atom to form distorted corner-sharing OBa2Nb2 trigonal pyramids.