BaCaCeHfO6 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 Hf(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 Hf(1)O6 octahedra. In the third Ba site, Ba(3) is bonded in a distorted square co-planar geometry to four equivalent O(2) atoms. In the fourth Ba site, Ba(4) is bonded in a distorted body-centered cubic geometry to four equivalent O(3) and four equivalent O(5) atoms. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted square co-planar geometry to four equivalent O(5) atoms. In the second Ca site, Ca(2) is bonded in a distorted body-centered cubic geometry to four equivalent O(2) and four equivalent O(6) atoms. In the third Ca site, Ca(3) is bonded in a square co-planar geometry to four equivalent O(4) atoms. In the fourth Ca site, Ca(4) is bonded in a square co-planar geometry to four equivalent O(1) 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 Hf(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 18-33°. Hf(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 HfO6 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 18-33°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Ba(2), one Ba(4), one Ca(1), one Ce(1), and one Hf(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Ba(2), one Ca(2), one Ce(1), and one Hf(1) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Ba(1), one Ca(4), one Ce(1), and one Hf(1) atom. In the fourth O site, O(2) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Ca(2), one Ce(1), and one Hf(1) atom. In the fifth O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(4), one Ce(1), and one Hf(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Ba(2), one Ca(3), one Ce(1), and one Hf(1) atom.
BaCaCeHfO6 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 Hf(1)O6 octahedra. All Ba(1)-O(1) bond lengths are 3.09 Å. All Ba(1)-O(2) bond lengths are 3.08 Å. All Ba(1)-O(3) bond lengths are 2.95 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 Hf(1)O6 octahedra. All Ba(2)-O(4) bond lengths are 2.96 Å. All Ba(2)-O(5) bond lengths are 3.04 Å. All Ba(2)-O(6) bond lengths are 2.93 Å. In the third Ba site, Ba(3) is bonded in a distorted square co-planar geometry to four equivalent O(2) atoms. All Ba(3)-O(2) bond lengths are 2.66 Å. In the fourth Ba site, Ba(4) is bonded in a distorted body-centered cubic geometry to four equivalent O(3) and four equivalent O(5) atoms. All Ba(4)-O(3) bond lengths are 2.67 Å. All Ba(4)-O(5) bond lengths are 3.08 Å. There are four inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted square co-planar geometry to four equivalent O(5) atoms. All Ca(1)-O(5) bond lengths are 2.40 Å. In the second Ca site, Ca(2) is bonded in a distorted body-centered cubic geometry to four equivalent O(2) and four equivalent O(6) atoms. All Ca(2)-O(2) bond lengths are 2.96 Å. All Ca(2)-O(6) bond lengths are 2.40 Å. In the third Ca site, Ca(3) is bonded in a square co-planar geometry to four equivalent O(4) atoms. All Ca(3)-O(4) bond lengths are 2.42 Å. In the fourth Ca site, Ca(4) is bonded in a square co-planar geometry to four equivalent O(1) atoms. All Ca(4)-O(1) bond lengths are 2.43 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 Hf(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 18-33°. The Ce(1)-O(1) bond length is 2.28 Å. The Ce(1)-O(2) bond length is 2.22 Å. The Ce(1)-O(3) bond length is 2.29 Å. The Ce(1)-O(4) bond length is 2.28 Å. The Ce(1)-O(5) bond length is 2.28 Å. The Ce(1)-O(6) bond length is 2.22 Å. Hf(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 HfO6 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 18-33°. The Hf(1)-O(1) bond length is 2.12 Å. The Hf(1)-O(2) bond length is 2.09 Å. The Hf(1)-O(3) bond length is 2.11 Å. The Hf(1)-O(4) bond length is 2.12 Å. The Hf(1)-O(5) bond length is 2.11 Å. The Hf(1)-O(6) bond length is 2.09 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a 3-coordinate geometry to one Ba(2), one Ba(4), one Ca(1), one Ce(1), and one Hf(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one Ba(2), one Ca(2), one Ce(1), and one Hf(1) atom. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Ba(1), one Ca(4), one Ce(1), and one Hf(1) atom. In the fourth O site, O(2) is bonded in a 5-coordinate geometry to one Ba(1), one Ba(3), one Ca(2), one Ce(1), and one Hf(1) atom. In the fifth O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(4), one Ce(1), and one Hf(1) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Ba(2), one Ca(3), one Ce(1), and one Hf(1) atom.