BaCa2Cu3O5 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 4-coordinate geometry to four equivalent Cu(4) and four equivalent O(1) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to four equivalent O(3) atoms. In the fourth Cu site, Cu(4) is bonded in a body-centered cubic geometry to eight equivalent Ba(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ca(2), and two equivalent Cu(1) atoms to form OBa2Ca2Cu2 octahedra that share corners with two equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(2)Ca4Cu2 octahedra,  an edgeedge with one O(2)Ca4Cu2 octahedra, edges with two equivalent O(1)Ba2Ca2Cu2 octahedra, and faces with four equivalent O(1)Ba2Ca2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 4-67°. In the second O site, O(2) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Cu(2) atoms to form OCa4Cu2 octahedra that share corners with two equivalent O(2)Ca4Cu2 octahedra, corners with six equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(3)Ca4Cu2 octahedra,  an edgeedge with one O(1)Ba2Ca2Cu2 octahedra,  an edgeedge with one O(3)Ca4Cu2 octahedra, edges with two equivalent O(2)Ca4Cu2 octahedra, and faces with four equivalent O(2)Ca4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 1-67°. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Cu(3) atoms to form a mixture of corner, edge, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°.
BaCa2Cu3O5 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 4-coordinate geometry to four equivalent Cu(4) and four equivalent O(1) atoms. All Ba(1)-Cu(4) bond lengths are 3.65 Å. All Ba(1)-O(1) bond lengths are 2.61 Å. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Ca(1)-O(2) bond lengths are 2.56 Å. All Ca(1)-O(3) bond lengths are 2.52 Å. In the second Ca site, Ca(2) is bonded in a body-centered cubic geometry to four equivalent O(1) and four equivalent O(2) atoms. All Ca(2)-O(1) bond lengths are 2.62 Å. All Ca(2)-O(2) bond lengths are 2.47 Å. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to four equivalent O(1) atoms. All Cu(1)-O(1) bond lengths are 1.98 Å. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to four equivalent O(2) atoms. All Cu(2)-O(2) bond lengths are 1.97 Å. In the third Cu site, Cu(3) is bonded in a square co-planar geometry to four equivalent O(3) atoms. All Cu(3)-O(3) bond lengths are 1.97 Å. In the fourth Cu site, Cu(4) is bonded in a body-centered cubic geometry to eight equivalent Ba(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), two equivalent Ca(2), and two equivalent Cu(1) atoms to form OBa2Ca2Cu2 octahedra that share corners with two equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(2)Ca4Cu2 octahedra,  an edgeedge with one O(2)Ca4Cu2 octahedra, edges with two equivalent O(1)Ba2Ca2Cu2 octahedra, and faces with four equivalent O(1)Ba2Ca2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 4-67°. In the second O site, O(2) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Cu(2) atoms to form OCa4Cu2 octahedra that share corners with two equivalent O(2)Ca4Cu2 octahedra, corners with six equivalent O(1)Ba2Ca2Cu2 octahedra, corners with six equivalent O(3)Ca4Cu2 octahedra,  an edgeedge with one O(1)Ba2Ca2Cu2 octahedra,  an edgeedge with one O(3)Ca4Cu2 octahedra, edges with two equivalent O(2)Ca4Cu2 octahedra, and faces with four equivalent O(2)Ca4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 1-67°. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Cu(3) atoms to form a mixture of corner, edge, and face-sharing OCa4Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-67°.