Ligand assisted digestion and formation of monodisperse FeCoS2 nanocrystalsElectronic supplementary information (ESI) available: Powder XRD pattern, size distribution histograms, TGA and ICP results. See DOI: 10.1039/c6cp04912e

Digestive ripening of bimetallic magnetic nanocrystals from uniform microsheets to spherical nanocrystals was observed in FeCoS 2 nanocrystals leading to the formation of monodisperse nanocrystals. Earlier examples of digestive ripening are associated with the transformation of polydisperse particles to monodisperse particles deriving energetic stabilization from the monodispersity. However, it is interesting to note that in the current case, not only did we observe a transformation from uniform sheets to spherical particles but we also observed it in the absence of thiol, the most commonly used digestive ripening agent. We have then studied the effect of ligands such as oleic acid and oleylamine responsible for this ripening process. Long chain acids were found to be majorly responsible for digestive ripening while the amines assist in the formation of microsheets. A plausible mechanism has then been proposed. The synthesis and shape transformation of bimetallic nanocrystals; the role of ligands in the digestion of microsheets towards the formation of spherical nanocrystals.