Process for preparation of micron-sized single curved crystals of metals

A process for the preparation of micron-sized particles having a controlled curvature, said particles spread over a supporting substrate and including a single-crystal first metal wrapped in a nanoporous structure, said process comprising:

• (i) providing said substrate;
• (ii) depositing vapours of the first metal and of a second metal on a surface of said substrate, thus forming a substrate deposited with either a thin film comprising said first and second metals, or two thin films each comprising a different metal of said first and second metals, wherein said metals deposited on said substrate are selected from Au, Ag, Ge, Cu, and Pt, and the atomic percentage ratio between said first metal and said second metal is such that upon annealing said film(s), said first metal and said second metal form a eutectic melt;
• (iii) annealing said film(s) for a sufficient time period to form said eutectic melt that spontaneously dewets into micron-sized droplets spread over said substrate;
• (iv) (a) cooling said eutectic melt to room temperature, or (b) continuing the annealing of step (iii) in an environment that contains oxygen, thereby removing the second metal from said eutectic melt, to consequently grow a single crystal of the first metal, wherein according to a phase diagram of the eutectic melt, in each one of said droplets, said single crystal is grown in the confined space of said droplet, has a controlled curvature determined by the curved shape of said confining droplet and is wrapped in a two-phase eutectic microstructure comprising the first metal and the second metal;
• (v) cooling the grown single crystals of the first metal wrapped in the two-phase eutectic microstructure comprising the first metal and the second metal to obtain micron-sized particles of the single-crystal first metal wrapped in a solid phase comprising said two metals;
• and
• (vi) removing the second metal from said solid phase, thereby obtaining the micron-sized particles of the single-crystal first metal wrapped in the nanoporous structure, said particles having a controlled curvature and being spread over the supporting substrate;
• wherein said substrate is inert relative to said thin film(s) formed in step (ii);
• and the eutectic melt in step (iii) dewets within a temperature range allowing dewetting to occur prior to diffusion intermixing with said substrate and/or oxidation.