Rb2Ta2O5 crystallizes in the orthorhombic Imma space group. Rb(1) is bonded in a 10-coordinate geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(2) atoms. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 1°. In the second Ta site, Ta(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Rb(1) and two equivalent Ta(1) atoms to form a mixture of distorted edge, face, and corner-sharing ORb4Ta2 octahedra. The corner-sharing octahedral tilt angles range from 0-59°. In the second O site, O(2) is bonded to four equivalent Rb(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted edge, face, and corner-sharing ORb4Ta2 octahedra. The corner-sharing octahedral tilt angles range from 0-59°. In the third O site, O(3) is bonded in a distorted linear geometry to four equivalent Rb(1) and two equivalent Ta(2) atoms.
Rb2Ta2O5 crystallizes in the orthorhombic Imma space group. Rb(1) is bonded in a 10-coordinate geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(2) atoms. Both Rb(1)-O(3) bond lengths are 2.95 Å. There are two shorter (2.85 Å) and two longer (2.87 Å) Rb(1)-O(1) bond lengths. There are a spread of Rb(1)-O(2) bond distances ranging from 2.86-2.99 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 1°. Both Ta(1)-O(2) bond lengths are 2.07 Å. All Ta(1)-O(1) bond lengths are 2.07 Å. In the second Ta site, Ta(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Ta(2)-O(2) bond lengths are 1.98 Å. Both Ta(2)-O(3) bond lengths are 1.94 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Rb(1) and two equivalent Ta(1) atoms to form a mixture of distorted edge, face, and corner-sharing ORb4Ta2 octahedra. The corner-sharing octahedral tilt angles range from 0-59°. In the second O site, O(2) is bonded to four equivalent Rb(1), one Ta(1), and one Ta(2) atom to form a mixture of distorted edge, face, and corner-sharing ORb4Ta2 octahedra. The corner-sharing octahedral tilt angles range from 0-59°. In the third O site, O(3) is bonded in a distorted linear geometry to four equivalent Rb(1) and two equivalent Ta(2) atoms.