NdTa3O9 crystallizes in the monoclinic P2_1/m space group. Nd(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(5), and four equivalent O(4) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 27-48°. In the second Ta site, Ta(2) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(6) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 30-48°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Nd(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Ta(2) atoms. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Nd(1) and two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Nd(1) and two equivalent Ta(1) atoms to form a mixture of distorted edge and corner-sharing ONd2Ta2 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nd(1), one Ta(1), and one Ta(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom.
NdTa3O9 crystallizes in the monoclinic P2_1/m space group. Nd(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(5), and four equivalent O(4) atoms. The Nd(1)-O(1) bond length is 2.46 Å. The Nd(1)-O(3) bond length is 2.48 Å. Both Nd(1)-O(5) bond lengths are 2.51 Å. There are two shorter (2.44 Å) and two longer (2.52 Å) Nd(1)-O(4) bond lengths. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 27-48°. The Ta(1)-O(1) bond length is 2.00 Å. The Ta(1)-O(3) bond length is 1.97 Å. The Ta(1)-O(5) bond length is 1.96 Å. The Ta(1)-O(6) bond length is 1.85 Å. There is one shorter (2.02 Å) and one longer (2.20 Å) Ta(1)-O(4) bond length. In the second Ta site, Ta(2) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(6) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 30-48°. Both Ta(2)-O(2) bond lengths are 1.95 Å. Both Ta(2)-O(5) bond lengths are 2.02 Å. Both Ta(2)-O(6) bond lengths are 1.99 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Nd(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a bent 150 degrees geometry to two equivalent Ta(2) atoms. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Nd(1) and two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Nd(1) and two equivalent Ta(1) atoms to form a mixture of distorted edge and corner-sharing ONd2Ta2 tetrahedra. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Nd(1), one Ta(1), and one Ta(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom.