Ca2Nb2O7 crystallizes in the cubic Fd-3m space group. Ca(1) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted CaO8 hexagonal bipyramids that share edges with six equivalent Ca(1)O8 hexagonal bipyramids and edges with six equivalent Nb(1)O6 octahedra. Nb(1) is bonded to six equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra and edges with six equivalent Ca(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) atoms to form corner-sharing OCa4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Nb(1) atoms.
Ca2Nb2O7 crystallizes in the cubic Fd-3m space group. Ca(1) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted CaO8 hexagonal bipyramids that share edges with six equivalent Ca(1)O8 hexagonal bipyramids and edges with six equivalent Nb(1)O6 octahedra. Both Ca(1)-O(1) bond lengths are 2.29 Å. All Ca(1)-O(2) bond lengths are 2.69 Å. Nb(1) is bonded to six equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra and edges with six equivalent Ca(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. All Nb(1)-O(2) bond lengths are 2.00 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) atoms to form corner-sharing OCa4 tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ca(1) and two equivalent Nb(1) atoms.