BaSrNb4O12 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with eight equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Nb(1)O6 octahedra. Sr(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(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(2), one O(3), and four equivalent O(1) 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 Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-1°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(1), one Sr(1), and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted square co-planar geometry to two equivalent Ba(1) and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Sr(1) and two equivalent Nb(1) atoms.
BaSrNb4O12 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with four equivalent Ba(1)O12 cuboctahedra, corners with eight equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Nb(1)O6 octahedra. All Ba(1)-O(2) bond lengths are 2.85 Å. All Ba(1)-O(1) bond lengths are 2.89 Å. Sr(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with eight equivalent Ba(1)O12 cuboctahedra, and faces with eight equivalent Nb(1)O6 octahedra. All Sr(1)-O(3) bond lengths are 2.85 Å. All Sr(1)-O(1) bond lengths are 2.82 Å. Nb(1) is bonded to one O(2), one O(3), and four equivalent O(1) 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 Sr(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-1°. The Nb(1)-O(2) bond length is 2.03 Å. The Nb(1)-O(3) bond length is 2.00 Å. All Nb(1)-O(1) bond lengths are 2.02 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to one Ba(1), one Sr(1), and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted square co-planar geometry to two equivalent Ba(1) and two equivalent Nb(1) atoms. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Sr(1) and two equivalent Nb(1) atoms.