Ordering of monodisperse Ni nanoclusters by templating on high-temperature reconstructedα-Al2O3(0001)

Abstract

We demonstrate that the characteristic reconstructed surface of α-alumina (Al2O3) acts as a nanotemplate for the growth of well-ordered monodisperse arrays ofNi nanoclusters. Due to the insulating nature of the substrate we use dynamicscanning force microscopy operated in the non-contact mode (NC-AFM) tocharacterize the nanotemplate, to examine the size and distribution of metallicclusters on the surface and to investigate their position with respect to the surfaceatomic structure. The present NC-AFM results for the interaction of Ni withα-Al2O3 are supported by density functional theory (DFT) calculations. The ability ofα-Al2O3(0001) to act as a nanotemplate is attributed to a spatially modulated affinity towards theaccommodation of Ni into the top layer by substituting the surface Al atoms at certainsites on the reconstructed surface formed by high-temperature annealing. The insulating template, demonstratedfor Al2O3, may be a generally attractive system for the study of nanostructures which need to beisolated from a conducting bulk.