Li2SrTa2O7 crystallizes in the tetragonal I4/mmm space group. Li(1) is bonded in a 4-coordinate geometry to four equivalent O(3) atoms. Sr(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Ta(1)O6 octahedra. Ta(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form TaO6 octahedra that share corners with five equivalent Ta(1)O6 octahedra and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(1) and two equivalent Ta(1) atoms to form distorted OSr4Ta2 octahedra that share corners with four equivalent O(1)Sr4Ta2 octahedra, corners with two equivalent O(3)Li4Ta trigonal bipyramids, and edges with four equivalent O(1)Sr4Ta2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a distorted linear geometry to two equivalent Sr(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded to four equivalent Li(1) and one Ta(1) atom to form distorted OLi4Ta trigonal bipyramids that share  a cornercorner with one O(1)Sr4Ta2 octahedra, corners with four equivalent O(3)Li4Ta trigonal bipyramids, and edges with four equivalent O(3)Li4Ta trigonal bipyramids. The corner-sharing octahedra are not tilted.
Li2SrTa2O7 crystallizes in the tetragonal I4/mmm space group. Li(1) is bonded in a 4-coordinate geometry to four equivalent O(3) atoms. All Li(1)-O(3) bond lengths are 2.05 Å. Sr(1) is bonded to four equivalent O(1) and eight equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Ta(1)O6 octahedra. All Sr(1)-O(1) bond lengths are 2.79 Å. All Sr(1)-O(2) bond lengths are 2.74 Å. Ta(1) is bonded to one O(1), one O(3), and four equivalent O(2) atoms to form TaO6 octahedra that share corners with five equivalent Ta(1)O6 octahedra and faces with four equivalent Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-11°. The Ta(1)-O(1) bond length is 2.10 Å. The Ta(1)-O(3) bond length is 1.87 Å. All Ta(1)-O(2) bond lengths are 1.98 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sr(1) and two equivalent Ta(1) atoms to form distorted OSr4Ta2 octahedra that share corners with four equivalent O(1)Sr4Ta2 octahedra, corners with two equivalent O(3)Li4Ta trigonal bipyramids, and edges with four equivalent O(1)Sr4Ta2 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded in a distorted linear geometry to two equivalent Sr(1) and two equivalent Ta(1) atoms. In the third O site, O(3) is bonded to four equivalent Li(1) and one Ta(1) atom to form distorted OLi4Ta trigonal bipyramids that share  a cornercorner with one O(1)Sr4Ta2 octahedra, corners with four equivalent O(3)Li4Ta trigonal bipyramids, and edges with four equivalent O(3)Li4Ta trigonal bipyramids. The corner-sharing octahedra are not tilted.