Self-assembly of CoPt3 nanoparticle rings based on phase-separated hexadecylamine droplet structure

We present experimental results on how CoPt3 nanoparticles (diameter of 6 nm) can be self-assembled in micron-sized ring patterns (diameter ranging from 0.6 to 1.5 mum). Our single-step approach is based on a combination of phase separation in a thin film of a binary mixture, leading to a bilayer structure, the subsequent decomposition of the top layer into droplets, and finally the deposition of the COPt3 nanoparticles at the edges of the evaporating droplets. The interpretation is based on a comparison of results obtained from each individual process.