Lu3TaO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Lu sites. In the first Lu site, Lu(1) is bonded to one O(3), two equivalent O(1), and four equivalent O(2) atoms to form distorted LuO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Lu(1)O7 pentagonal bipyramids, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Lu(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. In the second Lu site, Lu(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. Ta(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Lu(1)O7 pentagonal bipyramids, and edges with four equivalent Lu(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 34°. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Lu(1) and two equivalent Lu(2) atoms to form a mixture of edge and corner-sharing OLu4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Lu(2), two equivalent Lu(1), and one Ta(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Lu(1) and two equivalent Ta(1) atoms.
Lu3TaO7 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Lu sites. In the first Lu site, Lu(1) is bonded to one O(3), two equivalent O(1), and four equivalent O(2) atoms to form distorted LuO7 pentagonal bipyramids that share corners with two equivalent Ta(1)O6 octahedra, corners with three equivalent Lu(1)O7 pentagonal bipyramids, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Lu(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. The Lu(1)-O(3) bond length is 2.64 Å. There is one shorter (2.16 Å) and one longer (2.22 Å) Lu(1)-O(1) bond length. There are two shorter (2.23 Å) and two longer (2.36 Å) Lu(1)-O(2) bond lengths. In the second Lu site, Lu(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Lu(2)-O(1) bond lengths are 2.33 Å. All Lu(2)-O(2) bond lengths are 2.59 Å. Ta(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Lu(1)O7 pentagonal bipyramids, and edges with four equivalent Lu(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 34°. Both Ta(1)-O(3) bond lengths are 1.95 Å. All Ta(1)-O(2) bond lengths are 1.99 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Lu(1) and two equivalent Lu(2) atoms to form a mixture of edge and corner-sharing OLu4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Lu(2), two equivalent Lu(1), and one Ta(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Lu(1) and two equivalent Ta(1) atoms.