Ba2Ca2EuTi3(CuO7)2 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(1), four equivalent O(3), and four equivalent O(5) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with four equivalent Ca(1)O12 cuboctahedra,  a faceface with one Ca(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Cu(1)O5 square pyramids. Ca(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(4) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra,  a faceface with one Ba(1)O12 cuboctahedra, faces with five equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. Eu(1) is bonded in a body-centered cubic geometry to eight equivalent O(3) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(4), one O(5), and four equivalent O(1) atoms to form TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra,  a cornercorner with one Cu(1)O5 square pyramid, faces with four equivalent Ba(1)O12 cuboctahedra, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the second Ti site, Ti(2) is bonded to two equivalent O(4) and four equivalent O(2) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and faces with eight equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Cu(1) is bonded to one O(5) and four equivalent O(3) atoms to form CuO5 square pyramids that share  a cornercorner with one Ti(1)O6 octahedra, corners with four equivalent Cu(1)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Ca(1), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ca(1) and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Eu(1), and two equivalent Cu(1) atoms. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent Ca(1), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded to four equivalent Ba(1), one Ti(1), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing OBa4TiCu octahedra. The corner-sharing octahedral tilt angles are 7°.
Ba2Ca2EuTi3(CuO7)2 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(1), four equivalent O(3), and four equivalent O(5) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with four equivalent Ca(1)O12 cuboctahedra,  a faceface with one Ca(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Cu(1)O5 square pyramids. All Ba(1)-O(1) bond lengths are 2.96 Å. All Ba(1)-O(3) bond lengths are 3.07 Å. All Ba(1)-O(5) bond lengths are 2.77 Å. Ca(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(4) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra,  a faceface with one Ba(1)O12 cuboctahedra, faces with five equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. All Ca(1)-O(1) bond lengths are 2.65 Å. All Ca(1)-O(2) bond lengths are 2.80 Å. All Ca(1)-O(4) bond lengths are 2.77 Å. Eu(1) is bonded in a body-centered cubic geometry to eight equivalent O(3) atoms. All Eu(1)-O(3) bond lengths are 2.46 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(4), one O(5), and four equivalent O(1) atoms to form TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with four equivalent Ti(1)O6 octahedra,  a cornercorner with one Cu(1)O5 square pyramid, faces with four equivalent Ba(1)O12 cuboctahedra, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-6°. The Ti(1)-O(4) bond length is 1.98 Å. The Ti(1)-O(5) bond length is 1.93 Å. All Ti(1)-O(1) bond lengths are 1.96 Å. In the second Ti site, Ti(2) is bonded to two equivalent O(4) and four equivalent O(2) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, and faces with eight equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Both Ti(2)-O(4) bond lengths are 1.93 Å. All Ti(2)-O(2) bond lengths are 1.96 Å. Cu(1) is bonded to one O(5) and four equivalent O(3) atoms to form CuO5 square pyramids that share  a cornercorner with one Ti(1)O6 octahedra, corners with four equivalent Cu(1)O5 square pyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. The Cu(1)-O(5) bond length is 2.24 Å. All Cu(1)-O(3) bond lengths are 1.98 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to two equivalent Ba(1), two equivalent Ca(1), and two equivalent Ti(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Ca(1) and two equivalent Ti(2) atoms. In the third O site, O(3) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Eu(1), and two equivalent Cu(1) atoms. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent Ca(1), one Ti(1), and one Ti(2) atom. In the fifth O site, O(5) is bonded to four equivalent Ba(1), one Ti(1), and one Cu(1) atom to form a mixture of distorted edge and corner-sharing OBa4TiCu octahedra. The corner-sharing octahedral tilt angles are 7°.