The calcium based fullerenoïd Ca33Bi22.7Al48O139.05: An enantiomorphic structure of strontium aluminate

The aluminate Ca33Bi22.7Al48O139.05, having an enantiomorphic structure from the first fullerenoid oxide Sr33Bi24.25Al48O141.375, has been isolated. The structure, solved by X-ray single crystal diffraction is built up from an aluminate framework made of AlO4 tetrahedra connected through corners and forming a huge “Al84O210” sphere where the Al atoms are disposed like the carbon atoms in the C84 fullerene. Difference between the Ca and Sr-phases lies in the composition and the structure of the [BixOy] cluster stuffing the aluminate sphere. In the Ca-phase, the cluster formulated “Bi22.7O45.05” can be ideally described as built up from BiO6 octahedra, BiO4L trigonal bipyramids and BiO3L tetrahedra. The EDS chemical analyses reveal a large domain of cationic stoichiometry, as observed for the Sr-phase. The high resolution electron microscopy (HREM) images of regular zones are in good agreement with the images calculated from the single crystal structure.