Eu2Hf2O7 crystallizes in the cubic Fd-3m space group. Eu(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1) and six equivalent O(2) atoms. Hf(1) is bonded to six equivalent O(2) atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with twelve equivalent O(2)Eu2Hf2 tetrahedra, and edges with six equivalent O(2)Eu2Hf2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Eu(1) and two equivalent Hf(1) atoms to form distorted OEu2Hf2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with twelve equivalent O(2)Eu2Hf2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, and edges with four equivalent O(2)Eu2Hf2 tetrahedra.
Eu2Hf2O7 crystallizes in the cubic Fd-3m space group. Eu(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(1) and six equivalent O(2) atoms. Both Eu(1)-O(1) bond lengths are 2.29 Å. All Eu(1)-O(2) bond lengths are 2.56 Å. Hf(1) is bonded to six equivalent O(2) atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles are 51°. All Hf(1)-O(2) bond lengths are 2.06 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with twelve equivalent O(2)Eu2Hf2 tetrahedra, and edges with six equivalent O(2)Eu2Hf2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Eu(1) and two equivalent Hf(1) atoms to form distorted OEu2Hf2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with twelve equivalent O(2)Eu2Hf2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, and edges with four equivalent O(2)Eu2Hf2 tetrahedra.