UO3 crystallizes in the tetragonal I4_1/amd space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form edge-sharing UO6 octahedra. In the second U site, U(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There are three inequivalent O sites. In the first O site, O(3) is bonded in a trigonal planar geometry to one U(2) and two equivalent U(1) atoms. In the second O site, O(1) is bonded in a single-bond geometry to one U(2) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one U(1) and one U(2) atom.
UO3 crystallizes in the tetragonal I4_1/amd space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form edge-sharing UO6 octahedra. Both U(1)-O(2) bond lengths are 1.91 Å. All U(1)-O(3) bond lengths are 2.23 Å. In the second U site, U(2) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Both U(2)-O(1) bond lengths are 1.81 Å. Both U(2)-O(2) bond lengths are 2.34 Å. Both U(2)-O(3) bond lengths are 2.36 Å. There are three inequivalent O sites. In the first O site, O(3) is bonded in a trigonal planar geometry to one U(2) and two equivalent U(1) atoms. In the second O site, O(1) is bonded in a single-bond geometry to one U(2) atom. In the third O site, O(2) is bonded in a bent 150 degrees geometry to one U(1) and one U(2) atom.