Cu3Ti2Ta2O12 crystallizes in the monoclinic C2/m space group. Ti(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-40°. Ta(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with four equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(4) atoms. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to four equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Ti(1) and one Cu(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ta(1) and one Cu(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ti(1), one Ta(1), and one Cu(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ti(1), one Ta(1), and one Cu(1) atom.
Cu3Ti2Ta2O12 crystallizes in the monoclinic C2/m space group. Ti(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra and corners with four equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-40°. Both Ti(1)-O(1) bond lengths are 2.00 Å. Both Ti(1)-O(3) bond lengths are 1.99 Å. Both Ti(1)-O(4) bond lengths are 2.00 Å. Ta(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra and corners with four equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles are 40°. Both Ta(1)-O(2) bond lengths are 2.00 Å. Both Ta(1)-O(3) bond lengths are 2.00 Å. Both Ta(1)-O(4) bond lengths are 2.00 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a square co-planar geometry to four equivalent O(4) atoms. All Cu(1)-O(4) bond lengths are 1.98 Å. In the second Cu site, Cu(2) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cu(2)-O(1) bond lengths are 1.97 Å. Both Cu(2)-O(2) bond lengths are 1.98 Å. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Cu(3)-O(3) bond lengths are 1.98 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Ti(1) and one Cu(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Ta(1) and one Cu(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ti(1), one Ta(1), and one Cu(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ti(1), one Ta(1), and one Cu(1) atom.