LuTa3O9 crystallizes in the orthorhombic Pnma space group. Lu(1) is bonded in a 9-coordinate geometry to one O(2), one O(4), one O(5), two equivalent O(3), and four equivalent O(6) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. In the second Ta site, Ta(2) is bonded to one O(4), one O(5), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted TaO7 pentagonal bipyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids,  an edgeedge with one Ta(1)O6 octahedra, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ta(1) and two equivalent Ta(2) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Lu(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Lu(1) and two equivalent Ta(2) atoms. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Lu(1) and two equivalent Ta(2) atoms. In the fifth O site, O(5) is bonded in a distorted linear geometry to one Lu(1) and two equivalent Ta(2) atoms. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Lu(1), one Ta(1), and one Ta(2) atom.
LuTa3O9 crystallizes in the orthorhombic Pnma space group. Lu(1) is bonded in a 9-coordinate geometry to one O(2), one O(4), one O(5), two equivalent O(3), and four equivalent O(6) atoms. The Lu(1)-O(2) bond length is 2.31 Å. The Lu(1)-O(4) bond length is 2.75 Å. The Lu(1)-O(5) bond length is 2.58 Å. Both Lu(1)-O(3) bond lengths are 2.28 Å. There are two shorter (2.31 Å) and two longer (2.61 Å) Lu(1)-O(6) bond lengths. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(6) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. Both Ta(1)-O(1) bond lengths are 2.01 Å. Both Ta(1)-O(2) bond lengths are 2.01 Å. Both Ta(1)-O(6) bond lengths are 1.98 Å. In the second Ta site, Ta(2) is bonded to one O(4), one O(5), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form distorted TaO7 pentagonal bipyramids that share  a cornercorner with one Ta(1)O6 octahedra, corners with two equivalent Ta(2)O7 pentagonal bipyramids,  an edgeedge with one Ta(1)O6 octahedra, and edges with two equivalent Ta(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 38°. The Ta(2)-O(4) bond length is 1.98 Å. The Ta(2)-O(5) bond length is 1.94 Å. The Ta(2)-O(6) bond length is 2.25 Å. There is one shorter (2.07 Å) and one longer (2.14 Å) Ta(2)-O(1) bond length. There is one shorter (1.99 Å) and one longer (2.09 Å) Ta(2)-O(3) bond length. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ta(1) and two equivalent Ta(2) atoms. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to one Lu(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Lu(1) and two equivalent Ta(2) atoms. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Lu(1) and two equivalent Ta(2) atoms. In the fifth O site, O(5) is bonded in a distorted linear geometry to one Lu(1) and two equivalent Ta(2) atoms. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Lu(1), one Ta(1), and one Ta(2) atom.