Ba3TiTa4O15 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(12), one O(13), one O(14), one O(15), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) 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 Ta(2)O6 octahedra, faces with two equivalent Ta(3)O6 octahedra, and faces with two equivalent Ta(4)O6 octahedra. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(10), and two equivalent O(7) atoms. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(8), and two equivalent O(9) atoms. Ti(1) is bonded to one O(1), one O(3), one O(5), one O(9), and two equivalent O(12) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 7-39°. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(7), one O(8), one O(9), and two equivalent O(11) atoms to form TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ta(2)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra,  a cornercorner with one Ta(4)O6 octahedra, and corners with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-36°. In the second Ta site, Ta(2) is bonded to one O(10), one O(2), one O(4), one O(6), and two equivalent O(13) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(4)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-37°. In the third Ta site, Ta(3) is bonded to one O(2), one O(4), one O(5), one O(8), and two equivalent O(14) atoms to form TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-37°. In the fourth Ta site, Ta(4) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(15) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-39°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(2), one Ti(1), and one Ta(4) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(3), one Ta(2), and one Ta(3) atom. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Ba(1), one Ti(1), and one Ta(4) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Ba(1), one Ta(2), and one Ta(3) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Ta(3) atom. In the sixth O site, O(6) is bonded in a distorted linear geometry to two equivalent Ba(1), one Ta(2), and one Ta(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Ta(1), and one Ta(4) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Ta(1), and one Ta(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Ti(1), and one Ta(1) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Ta(1), and one Ta(2) atom. In the eleventh O site, O(11) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the twelfth O site, O(12) is bonded in a 1-coordinate geometry to one Ba(1) and two equivalent Ti(1) atoms. In the thirteenth O site, O(13) is bonded in a distorted linear geometry to one Ba(1) and two equivalent Ta(2) atoms. In the fourteenth O site, O(14) is bonded in a distorted linear geometry to one Ba(1) and two equivalent Ta(3) atoms. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Ba(1) and two equivalent Ta(4) atoms.
Ba3TiTa4O15 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(12), one O(13), one O(14), one O(15), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) 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 Ta(2)O6 octahedra, faces with two equivalent Ta(3)O6 octahedra, and faces with two equivalent Ta(4)O6 octahedra. The Ba(1)-O(12) bond length is 2.73 Å. The Ba(1)-O(13) bond length is 2.88 Å. The Ba(1)-O(14) bond length is 2.85 Å. The Ba(1)-O(15) bond length is 2.81 Å. There is one shorter (2.76 Å) and one longer (2.83 Å) Ba(1)-O(3) bond length. There is one shorter (2.86 Å) and one longer (2.90 Å) Ba(1)-O(4) bond length. There is one shorter (2.78 Å) and one longer (2.84 Å) Ba(1)-O(5) bond length. There is one shorter (2.84 Å) and one longer (2.88 Å) Ba(1)-O(6) bond length. In the second Ba site, Ba(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(10), and two equivalent O(7) atoms. There is one shorter (2.76 Å) and one longer (2.82 Å) Ba(2)-O(1) bond length. There is one shorter (2.94 Å) and one longer (3.03 Å) Ba(2)-O(10) bond length. There is one shorter (2.87 Å) and one longer (2.96 Å) Ba(2)-O(7) bond length. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(8), and two equivalent O(9) atoms. There is one shorter (2.84 Å) and one longer (2.88 Å) Ba(3)-O(2) bond length. There is one shorter (2.88 Å) and one longer (2.97 Å) Ba(3)-O(8) bond length. There is one shorter (2.84 Å) and one longer (2.95 Å) Ba(3)-O(9) bond length. Ti(1) is bonded to one O(1), one O(3), one O(5), one O(9), and two equivalent O(12) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 7-39°. The Ti(1)-O(1) bond length is 1.97 Å. The Ti(1)-O(3) bond length is 2.05 Å. The Ti(1)-O(5) bond length is 2.16 Å. The Ti(1)-O(9) bond length is 1.94 Å. There is one shorter (1.77 Å) and one longer (2.25 Å) Ti(1)-O(12) bond length. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(7), one O(8), one O(9), and two equivalent O(11) atoms to form TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ta(2)O6 octahedra,  a cornercorner with one Ta(3)O6 octahedra,  a cornercorner with one Ta(4)O6 octahedra, and corners with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-36°. The Ta(1)-O(10) bond length is 2.03 Å. The Ta(1)-O(7) bond length is 2.01 Å. The Ta(1)-O(8) bond length is 1.97 Å. The Ta(1)-O(9) bond length is 1.95 Å. There is one shorter (1.97 Å) and one longer (2.05 Å) Ta(1)-O(11) bond length. In the second Ta site, Ta(2) is bonded to one O(10), one O(2), one O(4), one O(6), and two equivalent O(13) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(4)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-37°. The Ta(2)-O(10) bond length is 1.94 Å. The Ta(2)-O(2) bond length is 2.01 Å. The Ta(2)-O(4) bond length is 2.04 Å. The Ta(2)-O(6) bond length is 2.03 Å. There is one shorter (1.96 Å) and one longer (2.06 Å) Ta(2)-O(13) bond length. In the third Ta site, Ta(3) is bonded to one O(2), one O(4), one O(5), one O(8), and two equivalent O(14) atoms to form TaO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra,  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-37°. The Ta(3)-O(2) bond length is 2.02 Å. The Ta(3)-O(4) bond length is 2.03 Å. The Ta(3)-O(5) bond length is 1.95 Å. The Ta(3)-O(8) bond length is 2.01 Å. There is one shorter (1.96 Å) and one longer (2.06 Å) Ta(3)-O(14) bond length. In the fourth Ta site, Ta(4) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(15) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and faces with two equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-39°. The Ta(4)-O(1) bond length is 2.01 Å. The Ta(4)-O(3) bond length is 2.02 Å. The Ta(4)-O(6) bond length is 2.06 Å. The Ta(4)-O(7) bond length is 1.95 Å. There is one shorter (1.97 Å) and one longer (2.05 Å) Ta(4)-O(15) bond length. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(2), one Ti(1), and one Ta(4) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(3), one Ta(2), and one Ta(3) atom. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Ba(1), one Ti(1), and one Ta(4) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Ba(1), one Ta(2), and one Ta(3) atom. In the fifth O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Ta(3) atom. In the sixth O site, O(6) is bonded in a distorted linear geometry to two equivalent Ba(1), one Ta(2), and one Ta(4) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Ta(1), and one Ta(4) atom. In the eighth O site, O(8) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Ta(1), and one Ta(3) atom. In the ninth O site, O(9) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(3), one Ti(1), and one Ta(1) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(2), one Ta(1), and one Ta(2) atom. In the eleventh O site, O(11) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the twelfth O site, O(12) is bonded in a 1-coordinate geometry to one Ba(1) and two equivalent Ti(1) atoms. In the thirteenth O site, O(13) is bonded in a distorted linear geometry to one Ba(1) and two equivalent Ta(2) atoms. In the fourteenth O site, O(14) is bonded in a distorted linear geometry to one Ba(1) and two equivalent Ta(3) atoms. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Ba(1) and two equivalent Ta(4) atoms.