LiSr3Ta4(O6F)2 crystallizes in the trigonal R-3m space group. Li(1) is bonded in a linear geometry to two equivalent F(1) atoms. Sr(1) is bonded to two equivalent O(2), four equivalent O(1), and two equivalent F(1) atoms to form distorted SrO6F2 hexagonal bipyramids that share edges with four equivalent Sr(1)O6F2 hexagonal bipyramids, edges with two equivalent Ta(2)O6 octahedra, and edges 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(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra, corners with four equivalent Ta(1)O6 octahedra, and edges with four equivalent Sr(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-45°. In the second Ta site, Ta(2) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with six equivalent Ta(1)O6 octahedra and edges with six equivalent Sr(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1) and two equivalent Ta(1) atoms. F(1) is bonded to one Li(1) and three equivalent Sr(1) atoms to form corner-sharing FSr3Li tetrahedra.
LiSr3Ta4(O6F)2 crystallizes in the trigonal R-3m space group. Li(1) is bonded in a linear geometry to two equivalent F(1) atoms. Both Li(1)-F(1) bond lengths are 1.97 Å. Sr(1) is bonded to two equivalent O(2), four equivalent O(1), and two equivalent F(1) atoms to form distorted SrO6F2 hexagonal bipyramids that share edges with four equivalent Sr(1)O6F2 hexagonal bipyramids, edges with two equivalent Ta(2)O6 octahedra, and edges with four equivalent Ta(1)O6 octahedra. Both Sr(1)-O(2) bond lengths are 2.69 Å. All Sr(1)-O(1) bond lengths are 2.67 Å. Both Sr(1)-F(1) bond lengths are 2.43 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form TaO6 octahedra that share corners with two equivalent Ta(2)O6 octahedra, corners with four equivalent Ta(1)O6 octahedra, and edges with four equivalent Sr(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-45°. Both Ta(1)-O(1) bond lengths are 2.02 Å. All Ta(1)-O(2) bond lengths are 2.01 Å. In the second Ta site, Ta(2) is bonded to six equivalent O(1) atoms to form TaO6 octahedra that share corners with six equivalent Ta(1)O6 octahedra and edges with six equivalent Sr(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 45°. All Ta(2)-O(1) bond lengths are 2.03 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Sr(1), one Ta(1), and one Ta(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1) and two equivalent Ta(1) atoms. F(1) is bonded to one Li(1) and three equivalent Sr(1) atoms to form corner-sharing FSr3Li tetrahedra.