Na2GdTa5O15 crystallizes in the tetragonal P4/mbm space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(5) atoms. Gd(1) is bonded to four equivalent O(1) and eight equivalent O(4) atoms to form GdO12 cuboctahedra that share faces with two equivalent Gd(1)O12 cuboctahedra and faces with eight equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. In the second Ta site, Ta(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with five equivalent Ta(2)O6 octahedra, and faces with two equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 12-41°. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(1), one Ta(1), and one Ta(2) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Gd(1) and two equivalent Ta(2) atoms. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Ta(2) atoms. In the fourth O site, O(3) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the fifth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(1) and two equivalent Ta(2) atoms.
Na2GdTa5O15 crystallizes in the tetragonal P4/mbm space group. Na(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(5) atoms. Both Na(1)-O(2) bond lengths are 2.72 Å. All Na(1)-O(5) bond lengths are 2.91 Å. Gd(1) is bonded to four equivalent O(1) and eight equivalent O(4) atoms to form GdO12 cuboctahedra that share faces with two equivalent Gd(1)O12 cuboctahedra and faces with eight equivalent Ta(2)O6 octahedra. All Gd(1)-O(1) bond lengths are 2.60 Å. All Gd(1)-O(4) bond lengths are 2.67 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles range from 0-32°. Both Ta(1)-O(3) bond lengths are 1.96 Å. All Ta(1)-O(5) bond lengths are 2.00 Å. In the second Ta site, Ta(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra, corners with five equivalent Ta(2)O6 octahedra, and faces with two equivalent Gd(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 12-41°. The Ta(2)-O(2) bond length is 2.00 Å. The Ta(2)-O(5) bond length is 1.92 Å. Both Ta(2)-O(1) bond lengths are 1.98 Å. There is one shorter (2.00 Å) and one longer (2.05 Å) Ta(2)-O(4) bond length. There are five inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Na(1), one Ta(1), and one Ta(2) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Gd(1) and two equivalent Ta(2) atoms. In the third O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1) and two equivalent Ta(2) atoms. In the fourth O site, O(3) is bonded in a linear geometry to two equivalent Ta(1) atoms. In the fifth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Gd(1) and two equivalent Ta(2) atoms.