Eu2O3 crystallizes in the trigonal P-3m1 space group. Eu(1) is bonded in a 7-coordinate geometry to three equivalent O(1) and four equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to six equivalent Eu(1) atoms to form OEu6 octahedra that share corners with twelve equivalent O(2)Eu4 tetrahedra, edges with six equivalent O(1)Eu6 octahedra, and edges with six equivalent O(2)Eu4 tetrahedra. In the second O site, O(2) is bonded to four equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with six equivalent O(1)Eu6 octahedra, corners with six equivalent O(2)Eu4 tetrahedra, edges with three equivalent O(1)Eu6 octahedra, and edges with three equivalent O(2)Eu4 tetrahedra. The corner-sharing octahedral tilt angles range from 17-57°.
Eu2O3 crystallizes in the trigonal P-3m1 space group. Eu(1) is bonded in a 7-coordinate geometry to three equivalent O(1) and four equivalent O(2) atoms. All Eu(1)-O(1) bond lengths are 2.60 Å. There are three shorter (2.27 Å) and one longer (2.38 Å) Eu(1)-O(2) bond length. There are two inequivalent O sites. In the first O site, O(1) is bonded to six equivalent Eu(1) atoms to form OEu6 octahedra that share corners with twelve equivalent O(2)Eu4 tetrahedra, edges with six equivalent O(1)Eu6 octahedra, and edges with six equivalent O(2)Eu4 tetrahedra. In the second O site, O(2) is bonded to four equivalent Eu(1) atoms to form OEu4 tetrahedra that share corners with six equivalent O(1)Eu6 octahedra, corners with six equivalent O(2)Eu4 tetrahedra, edges with three equivalent O(1)Eu6 octahedra, and edges with three equivalent O(2)Eu4 tetrahedra. The corner-sharing octahedral tilt angles range from 17-57°.