Gold Nanostructures by Directional Solid-state Decomposition

This study addresses a novel approach of obtaining gold nanostructures, via directional eutectoid decomposition and selective etching of Fe-Au alloys. The eutectoid transformation occurs at 2.3%Au, which agrees perfectly with existing DTA and calculated data. The results are thus experimentally supporting the calculated part of the binary Fe-Au phase diagram. Gold nanofibres were rectangular in shape, constrained with two perpendicular crystallographic directions, showing the faceted nature of the Au phase. In addition, it was shown that a range of gold nanostructures, including gold nanoparticles, short nanorods, and nanofibres might be achieved depending on the processing route. The uniformity and regularity of the obtained nanostructures are limited, due to a non-cooperative mechanism of the eutectoid transformation. These homomorph gold nanostructures have the same high potential as other gold nanostructures but also the advantage of being inherently organized in a single crystalline matrix.