Figure 1: Crystal structure of C12A7.
The electron density isosurface (0.5 × 10−6 e·pm−3) in [Ca24Al28O64]4+·4e− obtained by maximum entropy method analysis and superposed on the atomic structure of the unit cell determined by Rietveld analysis (Ca: yellow; Al: red; O: cyan). The framework charge can also be compensated by incorporation of anions into cages, whose occupancy is one-sixth in the case of divalent anions such as O2− and S2−, and one-third in the case of monovalent anions such as F−, OH− and H−.
