DOE OSTI2020
BaAl4(SbO6)2 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are four shorter (2.75 Å) and four longer (3.15 Å) Ba–O bond lengths. Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with two equivalent AlO6 octahedra, corners with two equivalent SbO6 octahedra, edges with two equivalent AlO6 octahedra, and edges with two equivalent SbO6 octahedra. The corner-sharing octahedra tilt angles range from 47–53°. There are a spread of Al–O bond distances ranging from 1.88–1.99 Å. Sb5+ is bonded to six O2- atoms to form SbO6 octahedra that share corners with four equivalent AlO6 octahedra and edges with four equivalent AlO6 octahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of Sb–O bond distances ranging from 1.97–2.04 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+, two equivalent Al3+, and one Sb5+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Al3+ and one Sb5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Al3+ and one Sb5+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Ba2+, two equivalent Al3+, and one Sb5+ atom.