Materials Data on Ba23U8O48 by Materials Project

Abstract

Ba23U8O48 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are four inequivalent Ba sites. In the first Ba site, Ba is bonded to six O atoms to form BaO6 octahedra that share corners with six UO6 octahedra and faces with four equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. All Ba–O bond lengths are 2.54 Å. In the second Ba site, Ba is bonded to twelve O atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent BaO12 cuboctahedra, faces with three equivalent BaO12 cuboctahedra, faces with four BaO6 octahedra, and faces with four UO6 octahedra. There are a spread of Ba–O bond distances ranging from 3.07–3.46 Å. In the third Ba site, Ba is bonded to six equivalent O atoms to form BaO6 octahedra that share corners with six equivalent UO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Ba–O bond lengths are 2.56 Å. In the fourth Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are three shorter (2.82 Å) and six longer (3.26 Å) Ba–O bond lengths. There are two inequivalent U sites. In the first U site, U is bonded to six equivalent O atoms to form UO6 octahedra that share corners with six equivalent BaO6 octahedra and faces with four equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All U–O bond lengths are 2.07 Å. In the second U site, U is bonded to six O atoms to form UO6 octahedra that share corners with five BaO6 octahedra and faces with four equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are a spread of U–O bond distances ranging from 2.05–2.16 Å. There are four inequivalent O sites. In the first O site, O is bonded in a distorted linear geometry to five Ba and one U atom. In the second O site, O is bonded to four equivalent Ba and one U atom to form distorted edge-sharing OBa4U square pyramids. In the third O site, O is bonded in a distorted square co-planar geometry to three Ba and one U atom. In the fourth O site, O is bonded in a distorted linear geometry to five Ba and one U atom.