CsSr2Ta3O10 crystallizes in the tetragonal P4/mmm space group. Cs(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. Sr(1) is bonded to four equivalent O(2), four equivalent O(3), and four equivalent O(4) atoms to form distorted SrO12 cuboctahedra that share corners with eight equivalent Sr(1)O12 cuboctahedra, faces with five equivalent Sr(1)O12 cuboctahedra, and faces with four equivalent Ta(1)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(4) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and faces with eight equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. In the second Ta site, Ta(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), and four equivalent O(2) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to four equivalent Cs(1) and one Ta(2) atom. In the second O site, O(2) is bonded to two equivalent Sr(1) and two equivalent Ta(2) atoms to form distorted OSr2Ta2 trigonal pyramids that share corners with four equivalent O(4)Sr4Ta2 octahedra, corners with four equivalent O(2)Sr2Ta2 trigonal pyramids, edges with four equivalent O(2)Sr2Ta2 trigonal pyramids, and faces with two equivalent O(4)Sr4Ta2 octahedra. The corner-sharing octahedral tilt angles are 53°. In the third O site, O(3) is bonded in a linear geometry to four equivalent Sr(1) and two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded to four equivalent Sr(1), one Ta(1), and one Ta(2) atom to form distorted OSr4Ta2 octahedra that share corners with five equivalent O(4)Sr4Ta2 octahedra, corners with eight equivalent O(2)Sr2Ta2 trigonal pyramids, edges with four equivalent O(4)Sr4Ta2 octahedra, and faces with four equivalent O(2)Sr2Ta2 trigonal pyramids. The corner-sharing octahedral tilt angles range from 0-12°.
CsSr2Ta3O10 crystallizes in the tetragonal P4/mmm space group. Cs(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Cs(1)-O(1) bond lengths are 3.27 Å. Sr(1) is bonded to four equivalent O(2), four equivalent O(3), and four equivalent O(4) atoms to form distorted SrO12 cuboctahedra that share corners with eight equivalent Sr(1)O12 cuboctahedra, faces with five equivalent Sr(1)O12 cuboctahedra, and faces with four equivalent Ta(1)O6 octahedra. All Sr(1)-O(2) bond lengths are 2.63 Å. All Sr(1)-O(3) bond lengths are 3.01 Å. All Sr(1)-O(4) bond lengths are 2.82 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(4) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and faces with eight equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Both Ta(1)-O(4) bond lengths are 1.98 Å. All Ta(1)-O(3) bond lengths are 1.99 Å. In the second Ta site, Ta(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), and four equivalent O(2) atoms. The Ta(2)-O(1) bond length is 1.79 Å. The Ta(2)-O(4) bond length is 2.42 Å. All Ta(2)-O(2) bond lengths are 2.03 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to four equivalent Cs(1) and one Ta(2) atom. In the second O site, O(2) is bonded to two equivalent Sr(1) and two equivalent Ta(2) atoms to form distorted OSr2Ta2 trigonal pyramids that share corners with four equivalent O(4)Sr4Ta2 octahedra, corners with four equivalent O(2)Sr2Ta2 trigonal pyramids, edges with four equivalent O(2)Sr2Ta2 trigonal pyramids, and faces with two equivalent O(4)Sr4Ta2 octahedra. The corner-sharing octahedral tilt angles are 53°. In the third O site, O(3) is bonded in a linear geometry to four equivalent Sr(1) and two equivalent Ta(1) atoms. In the fourth O site, O(4) is bonded to four equivalent Sr(1), one Ta(1), and one Ta(2) atom to form distorted OSr4Ta2 octahedra that share corners with five equivalent O(4)Sr4Ta2 octahedra, corners with eight equivalent O(2)Sr2Ta2 trigonal pyramids, edges with four equivalent O(4)Sr4Ta2 octahedra, and faces with four equivalent O(2)Sr2Ta2 trigonal pyramids. The corner-sharing octahedral tilt angles range from 0-12°.