Theoretical study of medium-sized clusters of (Al2O3)n - From single cage to core-shell cage

► Density functional theory calculations on single-cage and core-shell structures of (Al2O3)n. ► The medium-sized (Al2O3)n n > 40 clusters have the core-shell cage structures. ► The binding energy of (Al2O3)n core-shell clusters increases as the cluster size increases. ► The HOMO-LUMO gap is a useful indicator of the kinetic stability of these core-shell clusters.