Materials Data on Ba3Ac by Materials Project

Ba3Ac is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded to eight Ba and four equivalent Ac atoms to form BaBa8Ac4 cuboctahedra that share corners with twelve equivalent BaBa8Ac4 cuboctahedra, edges with eight equivalent AcBa12 cuboctahedra, edges with sixteen BaBa8Ac4 cuboctahedra, faces with four equivalent AcBa12 cuboctahedra, and faces with fourteen BaBa8Ac4 cuboctahedra. There are four shorter (4.29 Å) and four longer (4.34 Å) Ba–Ba bond lengths. All Ba–Ac bond lengths are 4.34 Å. In the second Ba site, Ba is bonded to eight equivalent Ba and four equivalent Ac atoms to form BaBa8Ac4 cuboctahedra that share corners with four equivalent BaBa8Ac4 cuboctahedra, corners with eight equivalent AcBa12 cuboctahedra, edges with twenty-four BaBa8Ac4 cuboctahedra, faces with six equivalent AcBa12 cuboctahedra, and faces with twelve BaBa8Ac4 cuboctahedra. All Ba–Ac bond lengths are 4.29 Å. Ac is bonded to twelve Ba atoms to form AcBa12 cuboctahedra that share corners with four equivalent AcBa12 cuboctahedra, corners with eight equivalent BaBa8Ac4 cuboctahedra, edges with eight equivalent AcBa12 cuboctahedra, edges with sixteen equivalent BaBa8Ac4 cuboctahedra, faces with four equivalent AcBa12 cuboctahedra, and faces with fourteen BaBa8Ac4 cuboctahedra.