KCeHf4O12 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 4-coordinate geometry to two equivalent O(3) and four equivalent O(5) atoms. Ce(1) is bonded to two equivalent O(2), two equivalent O(4), and four equivalent O(1) atoms to form distorted CeO8 hexagonal bipyramids that share edges with eight equivalent Hf(1)O6 octahedra. Hf(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form HfO6 octahedra that share corners with six equivalent Hf(1)O6 octahedra and edges with two equivalent Ce(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 11-31°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Hf(1) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one K(1) and two equivalent Hf(1) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ce(1) and two equivalent Hf(1) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Hf(1) atoms.
KCeHf4O12 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 4-coordinate geometry to two equivalent O(3) and four equivalent O(5) atoms. Both K(1)-O(3) bond lengths are 2.58 Å. There are two shorter (2.69 Å) and two longer (3.06 Å) K(1)-O(5) bond lengths. Ce(1) is bonded to two equivalent O(2), two equivalent O(4), and four equivalent O(1) atoms to form distorted CeO8 hexagonal bipyramids that share edges with eight equivalent Hf(1)O6 octahedra. Both Ce(1)-O(2) bond lengths are 2.49 Å. Both Ce(1)-O(4) bond lengths are 2.40 Å. All Ce(1)-O(1) bond lengths are 2.42 Å. Hf(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form HfO6 octahedra that share corners with six equivalent Hf(1)O6 octahedra and edges with two equivalent Ce(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 11-31°. The Hf(1)-O(2) bond length is 2.11 Å. The Hf(1)-O(3) bond length is 2.03 Å. The Hf(1)-O(4) bond length is 2.15 Å. The Hf(1)-O(5) bond length is 2.02 Å. Both Hf(1)-O(1) bond lengths are 2.10 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Hf(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Ce(1) and two equivalent Hf(1) atoms. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one K(1) and two equivalent Hf(1) atoms. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Ce(1) and two equivalent Hf(1) atoms. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent K(1) and two equivalent Hf(1) atoms.