BaCa(CoO3)4 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra, and faces with eight equivalent Co(1)O6 octahedra. Ca(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, corners with eight equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Co(1)O6 octahedra. Co(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Co(1)O6 octahedra, faces with two equivalent Ba(1)O12 cuboctahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-6°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted square co-planar geometry to one Ba(1), one Ca(1), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to two equivalent Ca(1) and two equivalent Co(1) atoms. In the third O site, O(3) is bonded in a distorted square co-planar geometry to two equivalent Ba(1) and two equivalent Co(1) atoms.
BaCa(CoO3)4 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra, and faces with eight equivalent Co(1)O6 octahedra. All Ba(1)-O(3) bond lengths are 2.69 Å. All Ba(1)-O(1) bond lengths are 2.79 Å. Ca(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, corners with eight equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Co(1)O6 octahedra. All Ca(1)-O(2) bond lengths are 2.69 Å. All Ca(1)-O(1) bond lengths are 2.57 Å. Co(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form CoO6 octahedra that share corners with six equivalent Co(1)O6 octahedra, faces with two equivalent Ba(1)O12 cuboctahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-6°. The Co(1)-O(2) bond length is 1.87 Å. The Co(1)-O(3) bond length is 1.91 Å. All Co(1)-O(1) bond lengths are 1.90 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted square co-planar geometry to one Ba(1), one Ca(1), and two equivalent Co(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to two equivalent Ca(1) and two equivalent Co(1) atoms. In the third O site, O(3) is bonded in a distorted square co-planar geometry to two equivalent Ba(1) and two equivalent Co(1) atoms.