Stacking faults and polymorphs in alumina nanorods

We investigated the stacking faults in gamma-alumina nanorods by means of high-resolution electron microscopy. Our results show that the ordered arrangement of stacking faults in gamma-alumina led to the transformation of gamma- to delta-alumina. We suggest that the alternative arrangement of (010)(a/4)[011] and (010)(a/4)[011] stacking faults induces the transformation. This model is in agreement with our experimental results and consistent with other investigations. Our work sheds some light on the long-disputed transition mechanism in metastable alumina polymorphs.