Eu2W2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Eu site, Eu(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form EuO12 cuboctahedra that share corners with four equivalent Eu(2)O12 cuboctahedra, faces with four equivalent Eu(2)O12 cuboctahedra, and faces with eight equivalent W(1)O5 square pyramids. W(1) is bonded to one O(2) and four equivalent O(1) atoms to form WO5 square pyramids that share corners with five equivalent W(1)O5 square pyramids and faces with four equivalent Eu(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Eu(1), two equivalent Eu(2), and two equivalent W(1) atoms to form a mixture of distorted edge, face, and corner-sharing OEu4W2 octahedra. The corner-sharing octahedral tilt angles range from 0-66°. In the second O site, O(2) is bonded to four equivalent Eu(2) and two equivalent W(1) atoms to form a mixture of distorted edge, face, and corner-sharing OEu4W2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°.
Eu2W2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Eu(1)-O(1) bond lengths are 2.67 Å. In the second Eu site, Eu(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form EuO12 cuboctahedra that share corners with four equivalent Eu(2)O12 cuboctahedra, faces with four equivalent Eu(2)O12 cuboctahedra, and faces with eight equivalent W(1)O5 square pyramids. All Eu(2)-O(2) bond lengths are 2.91 Å. All Eu(2)-O(1) bond lengths are 2.89 Å. W(1) is bonded to one O(2) and four equivalent O(1) atoms to form WO5 square pyramids that share corners with five equivalent W(1)O5 square pyramids and faces with four equivalent Eu(2)O12 cuboctahedra. The W(1)-O(2) bond length is 2.12 Å. All W(1)-O(1) bond lengths are 2.06 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Eu(1), two equivalent Eu(2), and two equivalent W(1) atoms to form a mixture of distorted edge, face, and corner-sharing OEu4W2 octahedra. The corner-sharing octahedral tilt angles range from 0-66°. In the second O site, O(2) is bonded to four equivalent Eu(2) and two equivalent W(1) atoms to form a mixture of distorted edge, face, and corner-sharing OEu4W2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°.