Ta9V2O25 crystallizes in the tetragonal I4/m space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(5) and four O(6,6) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(2) atoms to form a mixture of edge and corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 1-27°. In the third Ta site, Ta(3) is bonded to one O(2), one O(3), one O(4), one O(7), and two equivalent O(1) atoms to form distorted TaO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent V(1)O4 tetrahedra, and edges with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-27°. V(1) is bonded to four equivalent O(4) atoms to form distorted VO4 tetrahedra that share corners with four equivalent Ta(3)O6 octahedra and edges with two equivalent V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Ta(3) and two equivalent V(1) atoms. In the second O site, O(5) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the third O site, O(6) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the fourth O site, O(6) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the fifth O site, O(7) is bonded in a linear geometry to one Ta(2) and one Ta(3) atom. In the sixth O site, O(1) is bonded in a distorted T-shaped geometry to one Ta(2) and two equivalent Ta(3) atoms. In the seventh O site, O(2) is bonded in a distorted T-shaped geometry to one Ta(3) and two equivalent Ta(2) atoms. In the eighth O site, O(3) is bonded in a linear geometry to one Ta(2) and one Ta(3) atom.
Ta9V2O25 crystallizes in the tetragonal I4/m space group. There are three inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(5) and four O(6,6) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-1°. Both Ta(1)-O(5) bond lengths are 1.99 Å. All Ta(1)-O(6,6) bond lengths are 2.02 Å. In the second Ta site, Ta(2) is bonded to one O(1), one O(3), one O(6), one O(7), and two equivalent O(2) atoms to form a mixture of edge and corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 1-27°. The Ta(2)-O(1) bond length is 2.27 Å. The Ta(2)-O(3) bond length is 1.94 Å. The Ta(2)-O(6) bond length is 1.86 Å. The Ta(2)-O(7) bond length is 2.03 Å. Both Ta(2)-O(2) bond lengths are 2.05 Å. In the third Ta site, Ta(3) is bonded to one O(2), one O(3), one O(4), one O(7), and two equivalent O(1) atoms to form distorted TaO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent V(1)O4 tetrahedra, and edges with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 5-27°. The Ta(3)-O(2) bond length is 2.27 Å. The Ta(3)-O(3) bond length is 1.90 Å. The Ta(3)-O(4) bond length is 2.02 Å. The Ta(3)-O(7) bond length is 1.87 Å. Both Ta(3)-O(1) bond lengths are 2.05 Å. V(1) is bonded to four equivalent O(4) atoms to form distorted VO4 tetrahedra that share corners with four equivalent Ta(3)O6 octahedra and edges with two equivalent V(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. All V(1)-O(4) bond lengths are 1.92 Å. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Ta(3) and two equivalent V(1) atoms. In the second O site, O(5) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the third O site, O(6) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. In the fourth O site, O(6) is bonded in a linear geometry to one Ta(1) and one Ta(2) atom. The O(6)-Ta(2) bond length is 1.86 Å. In the fifth O site, O(7) is bonded in a linear geometry to one Ta(2) and one Ta(3) atom. In the sixth O site, O(1) is bonded in a distorted T-shaped geometry to one Ta(2) and two equivalent Ta(3) atoms. In the seventh O site, O(2) is bonded in a distorted T-shaped geometry to one Ta(3) and two equivalent Ta(2) atoms. In the eighth O site, O(3) is bonded in a linear geometry to one Ta(2) and one Ta(3) atom.