Materials Data on Ac2O3 by Materials Project
Ac2O3 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ac3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ac–O bond distances ranging from 2.47–2.84 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Ac3+ atoms to form OAc4 tetrahedra that share corners with six equivalent OAc6 octahedra, corners with six equivalent OAc4 tetrahedra, edges with three equivalent OAc6 octahedra, and edges with three equivalent OAc4 tetrahedra. The corner-sharing octahedra tilt angles range from 17–56°. In the second O2- site, O2- is bonded to six equivalent Ac3+ atoms to form OAc6 octahedra that share corners with twelve equivalent OAc4 tetrahedra, edges with six equivalent OAc6 octahedra, and edges with six equivalent OAc4 tetrahedra.