YBaCo2O5 crystallizes in the orthorhombic Pmma space group. Ba(1) is bonded to two equivalent O(1), two equivalent O(3), four equivalent O(2), and four equivalent O(4) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Co(1)O5 square pyramids, and faces with four equivalent Co(2)O5 trigonal bipyramids. Y(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form CoO5 square pyramids that share corners with two equivalent Co(1)O5 square pyramids, corners with three equivalent Co(2)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. In the second Co site, Co(2) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted CoO5 trigonal bipyramids that share corners with three equivalent Co(1)O5 square pyramids, corners with two equivalent Co(2)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Co(2) atoms. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Co(1), and one Co(2) atom to form a mixture of distorted edge and corner-sharing OBa4Co2 octahedra. The corner-sharing octahedra are not tilted.
YBaCo2O5 crystallizes in the orthorhombic Pmma space group. Ba(1) is bonded to two equivalent O(1), two equivalent O(3), four equivalent O(2), and four equivalent O(4) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Ba(1)O12 cuboctahedra, faces with four equivalent Co(1)O5 square pyramids, and faces with four equivalent Co(2)O5 trigonal bipyramids. Both Ba(1)-O(1) bond lengths are 3.07 Å. Both Ba(1)-O(3) bond lengths are 3.09 Å. All Ba(1)-O(2) bond lengths are 3.09 Å. All Ba(1)-O(4) bond lengths are 2.79 Å. Y(1) is bonded in a body-centered cubic geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms. Both Y(1)-O(1) bond lengths are 2.43 Å. Both Y(1)-O(3) bond lengths are 2.42 Å. All Y(1)-O(2) bond lengths are 2.43 Å. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded to one O(4), two equivalent O(1), and two equivalent O(2) atoms to form CoO5 square pyramids that share corners with two equivalent Co(1)O5 square pyramids, corners with three equivalent Co(2)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The Co(1)-O(4) bond length is 2.13 Å. Both Co(1)-O(1) bond lengths are 2.00 Å. Both Co(1)-O(2) bond lengths are 2.01 Å. In the second Co site, Co(2) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted CoO5 trigonal bipyramids that share corners with three equivalent Co(1)O5 square pyramids, corners with two equivalent Co(2)O5 trigonal bipyramids, and faces with four equivalent Ba(1)O12 cuboctahedra. The Co(2)-O(4) bond length is 1.82 Å. Both Co(2)-O(2) bond lengths are 2.00 Å. Both Co(2)-O(3) bond lengths are 2.04 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), one Co(1), and one Co(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Co(2) atoms. In the fourth O site, O(4) is bonded to four equivalent Ba(1), one Co(1), and one Co(2) atom to form a mixture of distorted edge and corner-sharing OBa4Co2 octahedra. The corner-sharing octahedra are not tilted.