Ca3Nb4(O6F)2 crystallizes in the trigonal R-3m space group. Ca(1) is bonded to two equivalent O(1), four equivalent O(2), and two equivalent F(1) atoms to form distorted CaO6F2 hexagonal bipyramids that share edges with four equivalent Ca(1)O6F2 hexagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Nb(2)O6 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(2)O6 octahedra and edges with six equivalent Ca(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. In the second Nb site, Nb(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and edges with four equivalent Ca(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-44°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1) and two equivalent Nb(2) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Nb(1), and one Nb(2) atom. F(1) is bonded in a trigonal planar geometry to three equivalent Ca(1) atoms.
Ca3Nb4(O6F)2 crystallizes in the trigonal R-3m space group. Ca(1) is bonded to two equivalent O(1), four equivalent O(2), and two equivalent F(1) atoms to form distorted CaO6F2 hexagonal bipyramids that share edges with four equivalent Ca(1)O6F2 hexagonal bipyramids, edges with two equivalent Nb(1)O6 octahedra, and edges with four equivalent Nb(2)O6 octahedra. Both Ca(1)-O(1) bond lengths are 2.63 Å. All Ca(1)-O(2) bond lengths are 2.67 Å. Both Ca(1)-F(1) bond lengths are 2.23 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to six equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(2)O6 octahedra and edges with six equivalent Ca(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. All Nb(1)-O(2) bond lengths are 2.00 Å. In the second Nb site, Nb(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with four equivalent Nb(2)O6 octahedra, and edges with four equivalent Ca(1)O6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-44°. Both Nb(2)-O(2) bond lengths are 2.01 Å. All Nb(2)-O(1) bond lengths are 2.01 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1) and two equivalent Nb(2) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1), one Nb(1), and one Nb(2) atom. F(1) is bonded in a trigonal planar geometry to three equivalent Ca(1) atoms.