Eu2Ga2O5 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 Ga(1)O5 square pyramids. Ga(1) is bonded to one O(2) and four equivalent O(1) atoms to form GaO5 square pyramids that share corners with five equivalent Ga(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 in a 6-coordinate geometry to two equivalent Eu(1), two equivalent Eu(2), and two equivalent Ga(1) atoms. In the second O site, O(2) is bonded to four equivalent Eu(2) and two equivalent Ga(1) atoms to form a mixture of distorted corner and edge-sharing OEu4Ga2 octahedra. The corner-sharing octahedra are not tilted.
Eu2Ga2O5 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 2.55 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 Ga(1)O5 square pyramids. All Eu(2)-O(2) bond lengths are 2.78 Å. All Eu(2)-O(1) bond lengths are 2.93 Å. Ga(1) is bonded to one O(2) and four equivalent O(1) atoms to form GaO5 square pyramids that share corners with five equivalent Ga(1)O5 square pyramids and faces with four equivalent Eu(2)O12 cuboctahedra. The Ga(1)-O(2) bond length is 1.90 Å. All Ga(1)-O(1) bond lengths are 1.99 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Eu(1), two equivalent Eu(2), and two equivalent Ga(1) atoms. In the second O site, O(2) is bonded to four equivalent Eu(2) and two equivalent Ga(1) atoms to form a mixture of distorted corner and edge-sharing OEu4Ga2 octahedra. The corner-sharing octahedra are not tilted.