DOE OSTI2020
Hf8PbO24 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded to six O atoms to form HfO6 octahedra that share corners with six HfO6 octahedra and a faceface with one PbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–11°. There are a spread of Hf–O bond distances ranging from 2.03–2.12 Å. In the second Hf site, Hf is bonded to six O atoms to form HfO6 octahedra that share corners with six HfO6 octahedra and a faceface with one PbO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–11°. There are a spread of Hf–O bond distances ranging from 2.03–2.12 Å. Pb is bonded to twelve O atoms to form PbO12 cuboctahedra that share faces with eight HfO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.77–2.79 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a linear geometry to two equivalent Hf atoms. In the second O site, O is bonded in a linear geometry to two equivalent Hf atoms. In the third O site, O is bonded in a distorted linear geometry to two Hf and one Pb atom. In the fourth O site, O is bonded in a distorted linear geometry to two equivalent Hf and one Pb atom. In the fifth O site, O is bonded in a linear geometry to two equivalent Hf and one Pb atom. In the sixth O site, O is bonded in a linear geometry to two equivalent Hf atoms. In the seventh O site, O is bonded in a linear geometry to two equivalent Hf atoms. In the eighth O site, O is bonded in a distorted linear geometry to two Hf and one Pb atom. In the ninth O site, O is bonded in a linear geometry to two Hf atoms.