Ca2HfO4 crystallizes in the orthorhombic Pbam space group. Ca(1) is bonded in a 7-coordinate geometry to three equivalent O(2) and four equivalent O(1) atoms. Hf(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing HfO6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and one Hf(1) atom to form a mixture of distorted corner and edge-sharing OCa4Hf trigonal bipyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to three equivalent Ca(1) and two equivalent Hf(1) atoms.
Ca2HfO4 crystallizes in the orthorhombic Pbam space group. Ca(1) is bonded in a 7-coordinate geometry to three equivalent O(2) and four equivalent O(1) atoms. There are a spread of Ca(1)-O(2) bond distances ranging from 2.36-2.85 Å. There are two shorter (2.35 Å) and two longer (2.36 Å) Ca(1)-O(1) bond lengths. Hf(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form edge-sharing HfO6 octahedra. Both Hf(1)-O(1) bond lengths are 2.05 Å. All Hf(1)-O(2) bond lengths are 2.12 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and one Hf(1) atom to form a mixture of distorted corner and edge-sharing OCa4Hf trigonal bipyramids. In the second O site, O(2) is bonded in a 5-coordinate geometry to three equivalent Ca(1) and two equivalent Hf(1) atoms.