RbLaTa2O7 crystallizes in the tetragonal P4/mmm space group. Rb(1) is bonded in a body-centered cubic geometry to eight equivalent O(3) atoms. La(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form a mixture of face and corner-sharing LaO12 cuboctahedra. Ta(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), and four equivalent O(2) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent La(1) and two equivalent Ta(1) atoms to form a mixture of corner and edge-sharing OLa4Ta2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent La(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a single-bond geometry to four equivalent Rb(1) and one Ta(1) atom.
RbLaTa2O7 crystallizes in the tetragonal P4/mmm space group. Rb(1) is bonded in a body-centered cubic geometry to eight equivalent O(3) atoms. All Rb(1)-O(3) bond lengths are 3.17 Å. La(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form a mixture of face and corner-sharing LaO12 cuboctahedra. All La(1)-O(1) bond lengths are 2.77 Å. All La(1)-O(2) bond lengths are 2.71 Å. Ta(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), and four equivalent O(2) atoms. The Ta(1)-O(1) bond length is 2.30 Å. The Ta(1)-O(3) bond length is 1.80 Å. All Ta(1)-O(2) bond lengths are 2.00 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent La(1) and two equivalent Ta(1) atoms to form a mixture of corner and edge-sharing OLa4Ta2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent La(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded in a single-bond geometry to four equivalent Rb(1) and one Ta(1) atom.