YBa2Cu3O6 crystallizes in the orthorhombic Pmm2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and four equivalent O(5) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(6) atoms. Y(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(5), two equivalent O(2), and two equivalent O(4) atoms to form corner-sharing CuO5 trigonal bipyramids. In the second Cu site, Cu(2) is bonded in a distorted T-shaped geometry to one O(6) and two equivalent O(3) atoms. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to one O(5), one O(6), and two equivalent O(1) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Cu(3) atoms to form a mixture of distorted edge, face, and corner-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 1-65°. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(2), two equivalent Y(1), and two equivalent Cu(2) atoms. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Cu(1) atoms. In the fifth O site, O(5) is bonded to four equivalent Ba(1), one Cu(1), and one Cu(3) atom to form a mixture of distorted edge, face, and corner-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the sixth O site, O(6) is bonded to four equivalent Ba(2), one Cu(2), and one Cu(3) atom to form a mixture of edge, face, and corner-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°.
YBa2Cu3O6 crystallizes in the orthorhombic Pmm2 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and four equivalent O(5) atoms. Both Ba(1)-O(1) bond lengths are 2.89 Å. Both Ba(1)-O(2) bond lengths are 3.05 Å. Both Ba(1)-O(4) bond lengths are 3.26 Å. All Ba(1)-O(5) bond lengths are 2.76 Å. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(3), and four equivalent O(6) atoms. Both Ba(2)-O(1) bond lengths are 2.76 Å. Both Ba(2)-O(3) bond lengths are 3.19 Å. All Ba(2)-O(6) bond lengths are 2.76 Å. Y(1) is bonded in a 6-coordinate geometry to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Y(1)-O(2) bond lengths are 2.37 Å. Both Y(1)-O(3) bond lengths are 2.50 Å. Both Y(1)-O(4) bond lengths are 2.21 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(5), two equivalent O(2), and two equivalent O(4) atoms to form corner-sharing CuO5 trigonal bipyramids. The Cu(1)-O(5) bond length is 2.32 Å. Both Cu(1)-O(2) bond lengths are 1.96 Å. Both Cu(1)-O(4) bond lengths are 2.02 Å. In the second Cu site, Cu(2) is bonded in a distorted T-shaped geometry to one O(6) and two equivalent O(3) atoms. The Cu(2)-O(6) bond length is 2.09 Å. Both Cu(2)-O(3) bond lengths are 1.99 Å. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to one O(5), one O(6), and two equivalent O(1) atoms. The Cu(3)-O(5) bond length is 1.91 Å. The Cu(3)-O(6) bond length is 1.98 Å. Both Cu(3)-O(1) bond lengths are 1.96 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Cu(3) atoms to form a mixture of distorted edge, face, and corner-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 1-65°. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(2), two equivalent Y(1), and two equivalent Cu(2) atoms. In the fourth O site, O(4) is bonded in a distorted see-saw-like geometry to two equivalent Ba(1), two equivalent Y(1), and two equivalent Cu(1) atoms. In the fifth O site, O(5) is bonded to four equivalent Ba(1), one Cu(1), and one Cu(3) atom to form a mixture of distorted edge, face, and corner-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-65°. In the sixth O site, O(6) is bonded to four equivalent Ba(2), one Cu(2), and one Cu(3) atom to form a mixture of edge, face, and corner-sharing OBa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°.