GdTa3O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(13), one O(15), one O(2), one O(4), one O(5), two equivalent O(16), two equivalent O(7), and three equivalent O(3) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(2)O12 cuboctahedra, corners with two equivalent Gd(1)O12 cuboctahedra, faces with two equivalent Gd(1)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Ta(4)O6 octahedra. In the second Gd site, Gd(2) is bonded to one O(17), one O(18), one O(2), one O(8), one O(9), two equivalent O(14), two equivalent O(6), and three equivalent O(1) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(1)O12 cuboctahedra, corners with two equivalent Gd(2)O12 cuboctahedra, faces with two equivalent Gd(2)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Ta(6)O6 octahedra. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(15), one O(17), one O(2), one O(4), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(5)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-16°. In the second Ta site, Ta(2) is bonded to one O(11), one O(13), one O(16), one O(3), one O(5), and one O(7) atom to form TaO6 octahedra that share corners with three equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(5)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the third Ta site, Ta(3) is bonded to one O(1), one O(12), one O(14), one O(18), one O(6), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(4)O6 octahedra, corners with two equivalent Ta(5)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-21°. In the fourth Ta site, Ta(4) is bonded to one O(12), one O(15), one O(16), one O(3), one O(4), and one O(7) atom to form TaO6 octahedra that share  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-17°. In the fifth Ta site, Ta(5) is bonded to one O(11), one O(13), one O(18), one O(2), one O(5), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. In the sixth Ta site, Ta(6) is bonded to one O(1), one O(10), one O(14), one O(17), one O(6), and one O(9) atom to form distorted TaO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-21°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to three equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Gd(1), one Gd(2), one Ta(1), and one Ta(5) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to three equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the eighth O site, O(8) is bonded in a distorted linear geometry to one Gd(2), one Ta(3), and one Ta(5) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Ta(6) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Ta(2) and one Ta(5) atom. In the twelfth O site, O(12) is bonded in a linear geometry to one Ta(3) and one Ta(4) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the sixteenth O site, O(16) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(3), and one Ta(5) atom.
GdTa3O9 crystallizes in the triclinic P-1 space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to one O(13), one O(15), one O(2), one O(4), one O(5), two equivalent O(16), two equivalent O(7), and three equivalent O(3) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(2)O12 cuboctahedra, corners with two equivalent Gd(1)O12 cuboctahedra, faces with two equivalent Gd(1)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Ta(4)O6 octahedra. The Gd(1)-O(13) bond length is 2.70 Å. The Gd(1)-O(15) bond length is 2.73 Å. The Gd(1)-O(2) bond length is 2.79 Å. The Gd(1)-O(4) bond length is 2.52 Å. The Gd(1)-O(5) bond length is 2.51 Å. There is one shorter (2.56 Å) and one longer (2.58 Å) Gd(1)-O(16) bond length. There is one shorter (2.73 Å) and one longer (2.76 Å) Gd(1)-O(7) bond length. There are a spread of Gd(1)-O(3) bond distances ranging from 2.62-2.97 Å. In the second Gd site, Gd(2) is bonded to one O(17), one O(18), one O(2), one O(8), one O(9), two equivalent O(14), two equivalent O(6), and three equivalent O(1) atoms to form distorted GdO12 cuboctahedra that share  a cornercorner with one Gd(1)O12 cuboctahedra, corners with two equivalent Gd(2)O12 cuboctahedra, faces with two equivalent Gd(2)O12 cuboctahedra,  a faceface with one Ta(1)O6 octahedra,  a faceface with one Ta(5)O6 octahedra, faces with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Ta(6)O6 octahedra. The Gd(2)-O(17) bond length is 2.62 Å. The Gd(2)-O(18) bond length is 2.63 Å. The Gd(2)-O(2) bond length is 2.97 Å. The Gd(2)-O(8) bond length is 2.83 Å. The Gd(2)-O(9) bond length is 2.83 Å. There is one shorter (2.61 Å) and one longer (2.62 Å) Gd(2)-O(14) bond length. Both Gd(2)-O(6) bond lengths are 2.49 Å. There are a spread of Gd(2)-O(1) bond distances ranging from 2.50-3.05 Å. There are six inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(10), one O(15), one O(17), one O(2), one O(4), and one O(9) atom to form TaO6 octahedra that share  a cornercorner with one Ta(5)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-16°. The Ta(1)-O(10) bond length is 1.97 Å. The Ta(1)-O(15) bond length is 2.00 Å. The Ta(1)-O(17) bond length is 1.98 Å. The Ta(1)-O(2) bond length is 1.98 Å. The Ta(1)-O(4) bond length is 1.99 Å. The Ta(1)-O(9) bond length is 1.99 Å. In the second Ta site, Ta(2) is bonded to one O(11), one O(13), one O(16), one O(3), one O(5), and one O(7) atom to form TaO6 octahedra that share corners with three equivalent Ta(4)O6 octahedra, corners with three equivalent Ta(5)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. The Ta(2)-O(11) bond length is 1.91 Å. The Ta(2)-O(13) bond length is 1.94 Å. The Ta(2)-O(16) bond length is 2.04 Å. The Ta(2)-O(3) bond length is 2.09 Å. The Ta(2)-O(5) bond length is 1.97 Å. The Ta(2)-O(7) bond length is 2.01 Å. In the third Ta site, Ta(3) is bonded to one O(1), one O(12), one O(14), one O(18), one O(6), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(4)O6 octahedra, corners with two equivalent Ta(5)O6 octahedra, corners with three equivalent Ta(6)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-21°. The Ta(3)-O(1) bond length is 2.08 Å. The Ta(3)-O(12) bond length is 1.92 Å. The Ta(3)-O(14) bond length is 2.05 Å. The Ta(3)-O(18) bond length is 1.95 Å. The Ta(3)-O(6) bond length is 2.07 Å. The Ta(3)-O(8) bond length is 1.92 Å. In the fourth Ta site, Ta(4) is bonded to one O(12), one O(15), one O(16), one O(3), one O(4), and one O(7) atom to form TaO6 octahedra that share  a cornercorner with one Ta(3)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and faces with three equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 4-17°. The Ta(4)-O(12) bond length is 1.94 Å. The Ta(4)-O(15) bond length is 1.92 Å. The Ta(4)-O(16) bond length is 2.06 Å. The Ta(4)-O(3) bond length is 2.05 Å. The Ta(4)-O(4) bond length is 1.97 Å. The Ta(4)-O(7) bond length is 2.01 Å. In the fifth Ta site, Ta(5) is bonded to one O(11), one O(13), one O(18), one O(2), one O(5), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra,  a faceface with one Gd(1)O12 cuboctahedra, and  a faceface with one Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 3-17°. The Ta(5)-O(11) bond length is 1.96 Å. The Ta(5)-O(13) bond length is 1.99 Å. The Ta(5)-O(18) bond length is 1.98 Å. The Ta(5)-O(2) bond length is 1.99 Å. The Ta(5)-O(5) bond length is 1.99 Å. The Ta(5)-O(8) bond length is 1.99 Å. In the sixth Ta site, Ta(6) is bonded to one O(1), one O(10), one O(14), one O(17), one O(6), and one O(9) atom to form distorted TaO6 octahedra that share corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Ta(3)O6 octahedra, and faces with three equivalent Gd(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 5-21°. The Ta(6)-O(1) bond length is 2.11 Å. The Ta(6)-O(10) bond length is 1.90 Å. The Ta(6)-O(14) bond length is 2.04 Å. The Ta(6)-O(17) bond length is 1.96 Å. The Ta(6)-O(6) bond length is 2.06 Å. The Ta(6)-O(9) bond length is 1.92 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to three equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the second O site, O(2) is bonded in a distorted linear geometry to one Gd(1), one Gd(2), one Ta(1), and one Ta(5) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to three equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the eighth O site, O(8) is bonded in a distorted linear geometry to one Gd(2), one Ta(3), and one Ta(5) atom. In the ninth O site, O(9) is bonded in a distorted linear geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the tenth O site, O(10) is bonded in a linear geometry to one Ta(1) and one Ta(6) atom. In the eleventh O site, O(11) is bonded in a linear geometry to one Ta(2) and one Ta(5) atom. In the twelfth O site, O(12) is bonded in a linear geometry to one Ta(3) and one Ta(4) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Gd(1), one Ta(2), and one Ta(5) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to two equivalent Gd(2), one Ta(3), and one Ta(6) atom. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Gd(1), one Ta(1), and one Ta(4) atom. In the sixteenth O site, O(16) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(1), one Ta(2), and one Ta(4) atom. In the seventeenth O site, O(17) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(1), and one Ta(6) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Gd(2), one Ta(3), and one Ta(5) atom.