BaSrCeNbO6 is Orthorhombic Perovskite-derived structured and crystallizes in the orthorhombic P222 space group. There are four inequivalent Ba sites. In the first Ba site, 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 faces with four equivalent Ce(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the second Ba site, Ba(2) is bonded to four equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form BaO12 cuboctahedra that share faces with four equivalent Ce(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(6) atoms. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(6) atoms. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted square co-planar geometry to four equivalent O(1) and four equivalent O(5) atoms. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to four equivalent O(3) and four equivalent O(4) atoms. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(4) atoms. In the fourth Sr site, Sr(4) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(3) and four equivalent O(5) atoms. Ce(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CeO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-24°. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with six equivalent Ce(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-24°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 5-coordinate geometry to one Ba(2), one Sr(1), one Sr(4), one Ce(1), and one Nb(1) atom. In the second O site, O(6) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ba(4), one Ce(1), and one Nb(1) atom. In the third O site, O(1) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(4), one Sr(1), one Ce(1), and one Nb(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(3), one Sr(3), one Ce(1), and one Nb(1) atom. In the fifth O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), one Sr(2), one Sr(4), one Ce(1), and one Nb(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Ba(2), one Sr(2), one Sr(3), one Ce(1), and one Nb(1) atom.
BaSrCeNbO6 is Orthorhombic Perovskite-derived structured and crystallizes in the orthorhombic P222 space group. There are four inequivalent Ba sites. In the first Ba site, 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 faces with four equivalent Ce(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 3.01 Å. All Ba(1)-O(2) bond lengths are 3.03 Å. All Ba(1)-O(3) bond lengths are 3.08 Å. In the second Ba site, Ba(2) is bonded to four equivalent O(4), four equivalent O(5), and four equivalent O(6) atoms to form BaO12 cuboctahedra that share faces with four equivalent Ce(1)O6 octahedra and faces with four equivalent Nb(1)O6 octahedra. All Ba(2)-O(4) bond lengths are 3.05 Å. All Ba(2)-O(5) bond lengths are 3.05 Å. All Ba(2)-O(6) bond lengths are 3.03 Å. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(6) atoms. All Ba(3)-O(2) bond lengths are 3.10 Å. All Ba(3)-O(6) bond lengths are 2.70 Å. In the fourth Ba site, Ba(4) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(6) atoms. All Ba(4)-O(1) bond lengths are 2.70 Å. All Ba(4)-O(6) bond lengths are 3.08 Å. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted square co-planar geometry to four equivalent O(1) and four equivalent O(5) atoms. All Sr(1)-O(1) bond lengths are 3.10 Å. All Sr(1)-O(5) bond lengths are 2.59 Å. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to four equivalent O(3) and four equivalent O(4) atoms. All Sr(2)-O(3) bond lengths are 3.07 Å. All Sr(2)-O(4) bond lengths are 2.58 Å. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to four equivalent O(2) and four equivalent O(4) atoms. All Sr(3)-O(2) bond lengths are 2.60 Å. All Sr(3)-O(4) bond lengths are 3.10 Å. In the fourth Sr site, Sr(4) is bonded in a distorted rectangular see-saw-like geometry to four equivalent O(3) and four equivalent O(5) atoms. All Sr(4)-O(3) bond lengths are 2.57 Å. All Sr(4)-O(5) bond lengths are 3.08 Å. Ce(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form CeO6 octahedra that share corners with six equivalent Nb(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-24°. The Ce(1)-O(1) bond length is 2.31 Å. The Ce(1)-O(2) bond length is 2.36 Å. The Ce(1)-O(3) bond length is 2.30 Å. The Ce(1)-O(4) bond length is 2.33 Å. The Ce(1)-O(5) bond length is 2.30 Å. The Ce(1)-O(6) bond length is 2.34 Å. Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NbO6 octahedra that share corners with six equivalent Ce(1)O6 octahedra,  a faceface with one Ba(1)O12 cuboctahedra, and  a faceface with one Ba(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 19-24°. The Nb(1)-O(1) bond length is 2.04 Å. The Nb(1)-O(2) bond length is 2.07 Å. The Nb(1)-O(3) bond length is 2.04 Å. The Nb(1)-O(4) bond length is 2.06 Å. The Nb(1)-O(5) bond length is 2.05 Å. The Nb(1)-O(6) bond length is 2.05 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 5-coordinate geometry to one Ba(2), one Sr(1), one Sr(4), one Ce(1), and one Nb(1) atom. In the second O site, O(6) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Ba(4), one Ce(1), and one Nb(1) atom. In the third O site, O(1) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(4), one Sr(1), one Ce(1), and one Nb(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to one Ba(1), one Ba(3), one Sr(3), one Ce(1), and one Nb(1) atom. In the fifth O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), one Sr(2), one Sr(4), one Ce(1), and one Nb(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Ba(2), one Sr(2), one Sr(3), one Ce(1), and one Nb(1) atom.