A New Approach to the Fabrication of “Smart” Near-Surface Nanostructure Composites

Abstract

A new method for the formation of “smarts” near-surface nanoscale composites has been developed. In this approach, small precipitates of active phases are embedded in the near-surface region of the material that is to be modified by a combination of ion implantation and thermal processing. The dispersion, concentration, and microstructure of the nanocrystals formed in the substrate material can be tailored through a careful choice of processing parameters-making this approach well suited to high-value-added, high-technology applications. The applicability of this approach to forming ”smart” surfaces on otherwise inactive materials was established in the case of VO₂ precipitates which were embedded in A1₂O₃ single crystals to create a medium suitable for optical applications-including optical data storage. Most recently, this concept has been extended to the fabrication of magnetic-field-sensitive nanostructured surfaces by forming magnetostrictive precipitates of materials such as Ni or RFe₂ (with R = Tm, Tb, Sm) that are embedded in various single-crystal-oxide hosts. These nanostructured, active surface composites have been characterized using XRD, RBS, TEM, and magneto-optical techniques.