Materials Data on Ca6HfO8 by Materials Project
Ca6HfO8 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent CaO6 octahedra, edges with two equivalent HfO6 octahedra, and edges with eight equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–14°. There are two shorter (2.40 Å) and four longer (2.42 Å) Ca–O bond lengths. Hf4+ is bonded to six equivalent O2- atoms to form HfO6 octahedra that share edges with twelve equivalent CaO6 octahedra. All Hf–O bond lengths are 2.11 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Ca2+ and one Hf4+ atom to form OCa4Hf square pyramids that share corners with nine equivalent OCa4Hf square pyramids, edges with four equivalent OCa6 octahedra, and edges with four equivalent OCa4Hf square pyramids. In the second O2- site, O2- is bonded to six equivalent Ca2+ atoms to form OCa6 octahedra that share corners with six equivalent OCa6 octahedra and edges with twelve equivalent OCa4Hf square pyramids. The corner-sharing octahedral tilt angles are 0°.