Dy2Ge2O7 crystallizes in the cubic Fd-3m space group. Dy(1) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted DyO8 hexagonal bipyramids that share edges with six equivalent Dy(1)O8 hexagonal bipyramids and edges with six equivalent Ge(1)O6 octahedra. Ge(1) is bonded to six equivalent O(2) atoms to form GeO6 octahedra that share corners with six equivalent Ge(1)O6 octahedra and edges with six equivalent Dy(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 47°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Dy(1) atoms to form ODy4 tetrahedra that share corners with four equivalent O(1)Dy4 tetrahedra, corners with twelve equivalent O(2)Dy2Ge2 tetrahedra, and edges with six equivalent O(2)Dy2Ge2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Dy(1) and two equivalent Ge(1) atoms to form distorted ODy2Ge2 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with twelve equivalent O(2)Dy2Ge2 tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with four equivalent O(2)Dy2Ge2 tetrahedra.
Dy2Ge2O7 crystallizes in the cubic Fd-3m space group. Dy(1) is bonded to two equivalent O(1) and six equivalent O(2) atoms to form distorted DyO8 hexagonal bipyramids that share edges with six equivalent Dy(1)O8 hexagonal bipyramids and edges with six equivalent Ge(1)O6 octahedra. Both Dy(1)-O(1) bond lengths are 2.15 Å. All Dy(1)-O(2) bond lengths are 2.45 Å. Ge(1) is bonded to six equivalent O(2) atoms to form GeO6 octahedra that share corners with six equivalent Ge(1)O6 octahedra and edges with six equivalent Dy(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 47°. All Ge(1)-O(2) bond lengths are 1.91 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Dy(1) atoms to form ODy4 tetrahedra that share corners with four equivalent O(1)Dy4 tetrahedra, corners with twelve equivalent O(2)Dy2Ge2 tetrahedra, and edges with six equivalent O(2)Dy2Ge2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Dy(1) and two equivalent Ge(1) atoms to form distorted ODy2Ge2 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with twelve equivalent O(2)Dy2Ge2 tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with four equivalent O(2)Dy2Ge2 tetrahedra.