Materials Data on Ho2Hf2O7 by Materials Project
Ho2Hf2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Ho3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.27 Å) and six longer (2.51 Å) Ho–O bond lengths. Hf4+ is bonded to six equivalent O2- atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedral tilt angles are 53°. All Hf–O bond lengths are 2.07 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Ho3+ and two equivalent Hf4+ atoms to form a mixture of distorted corner and edge-sharing OHo2Hf2 tetrahedra. In the second O2- site, O2- is bonded to four equivalent Ho3+ atoms to form OHo4 tetrahedra that share corners with sixteen OHo4 tetrahedra and edges with six equivalent OHo2Hf2 tetrahedra.