EuO2 crystallizes in the tetragonal P4/nmm space group. Eu(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Eu(1) atoms to form distorted OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with twelve equivalent O(2)Eu5 trigonal bipyramids, edges with four equivalent O(1)Eu4 tetrahedra, and edges with four equivalent O(2)Eu5 trigonal bipyramids. In the second O site, O(2) is bonded to five equivalent Eu(1) atoms to form distorted OEu5 trigonal bipyramids that share corners with twelve equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(2)Eu5 trigonal bipyramids, edges with four equivalent O(1)Eu4 tetrahedra, and edges with eight equivalent O(2)Eu5 trigonal bipyramids.
EuO2 crystallizes in the tetragonal P4/nmm space group. Eu(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. All Eu(1)-O(1) bond lengths are 2.39 Å. There is one shorter (2.33 Å) and four longer (2.59 Å) Eu(1)-O(2) bond lengths. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Eu(1) atoms to form distorted OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with twelve equivalent O(2)Eu5 trigonal bipyramids, edges with four equivalent O(1)Eu4 tetrahedra, and edges with four equivalent O(2)Eu5 trigonal bipyramids. In the second O site, O(2) is bonded to five equivalent Eu(1) atoms to form distorted OEu5 trigonal bipyramids that share corners with twelve equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(2)Eu5 trigonal bipyramids, edges with four equivalent O(1)Eu4 tetrahedra, and edges with eight equivalent O(2)Eu5 trigonal bipyramids.