Surface superstructures of ordered layers of Al2O3 on Ni3Al(001)

Atomically ordered Al2O3 obtained by thermal oxidation of the Ni3Al(001) surface Was Studied using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). LEED analysis has shown that oxidation Lit 800 and 1100 K forms two different structural phases of Al2O3. Detailed STM studies of both phases also reveal remarkable differences in surface pattern structure and arrangement of the domains. We have shown that well-ordered Al2O3 layers are. in principle, full of dislocations. However, the dislocations, which are responsible for surface Superstructures, Lire well ordered, forming either stripes in the low-temperature phase, or patches in the high-temperature phase. Interacting with the single-crystalline substrate, the nanopatches form their own lattice of superarrangement, introducing linelike or more complex Super-dislocations.