BaCaNb4O12 crystallizes in the orthorhombic Cmmm space group. Ba(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) 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 Nb(1)O6 octahedra. 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 Ca(1)O12 cuboctahedra, corners with eight equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Nb(1)O6 octahedra. Nb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(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 0-5°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(1), one Ca(1), and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to one Ba(1), one Ca(1), and two equivalent Nb(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 Nb(1) atoms. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Ca(1) and two equivalent Nb(1) atoms.
BaCaNb4O12 crystallizes in the orthorhombic Cmmm space group. Ba(1) is bonded to four equivalent O(1), four equivalent O(2), and four equivalent O(3) 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 Nb(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 2.85 Å. All Ba(1)-O(2) bond lengths are 2.95 Å. All Ba(1)-O(3) bond lengths are 2.85 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 Ca(1)O12 cuboctahedra, corners with eight equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Nb(1)O6 octahedra. All Ca(1)-O(1) bond lengths are 2.84 Å. All Ca(1)-O(2) bond lengths are 2.74 Å. All Ca(1)-O(4) bond lengths are 2.85 Å. Nb(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form NbO6 octahedra that share corners with six equivalent Nb(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 0-5°. The Nb(1)-O(3) bond length is 2.04 Å. The Nb(1)-O(4) bond length is 1.99 Å. Both Nb(1)-O(1) bond lengths are 2.01 Å. Both Nb(1)-O(2) bond lengths are 2.02 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(1), one Ca(1), and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to one Ba(1), one Ca(1), and two equivalent Nb(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 Nb(1) atoms. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Ca(1) and two equivalent Nb(1) atoms.