Eu2Ti2O5 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 Ti(1)O5 square pyramids. Ti(1) is bonded to one O(2) and four equivalent O(1) atoms to form TiO5 square pyramids that share corners with five equivalent Ti(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 Ti(1) atoms to form a mixture of distorted edge, face, and corner-sharing OEu4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Eu(2) and two equivalent Ti(1) atoms.
Eu2Ti2O5 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 2.59 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 Ti(1)O5 square pyramids. All Eu(2)-O(2) bond lengths are 2.80 Å. All Eu(2)-O(1) bond lengths are 2.86 Å. Ti(1) is bonded to one O(2) and four equivalent O(1) atoms to form TiO5 square pyramids that share corners with five equivalent Ti(1)O5 square pyramids and faces with four equivalent Eu(2)O12 cuboctahedra. The Ti(1)-O(2) bond length is 1.97 Å. All Ti(1)-O(1) bond lengths are 1.98 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 Ti(1) atoms to form a mixture of distorted edge, face, and corner-sharing OEu4Ti2 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Eu(2) and two equivalent Ti(1) atoms.