Materials Data on Sr3Hf2O7 by Materials Project
Sr3Hf2O7 crystallizes in the orthorhombic Ccce space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.46–3.12 Å. In the second Sr2+ site, Sr2+ is bonded in a 12-coordinate geometry to eight O2- atoms. There are four shorter (2.65 Å) and four longer (2.89 Å) Sr–O bond lengths. Hf4+ is bonded to six O2- atoms to form corner-sharing HfO6 octahedra. The corner-sharing octahedra tilt angles range from 0–22°. There are a spread of Hf–O bond distances ranging from 2.08–2.11 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded to five equivalent Sr2+ and one Hf4+ atom to form a mixture of distorted edge and corner-sharing OSr5Hf octahedra. The corner-sharing octahedral tilt angles are 7°. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and two equivalent Hf4+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to four equivalent Sr2+ and two equivalent Hf4+ atoms.