Facile directing agent-free synthesis and magnetism of nanocrystalline Fe-Ni alloy with tunable shape

This article reports the synthesis of nanocrystalline (nc) Fe20Ni80 particles with tunable shape, using a heterogeneous directing agent-free aqueous wet chemical method of mild synthesis conditions. The particle morphology has been controlled by varying synthesis conditions. The results demonstrate that the morphology of alloy particles changes from quasi-isotropic to anisotropic architecture by decreasing concentration of metal ions or increasing pH of reaction solution. Deep interpretations of such phenomena are reported. Magnetic behavior of the alloy is driven away from soft magnetic and toward hard magnetic behavior, by anisotropy and size reduction of alloy particles. This broadens practical applications of nc Fe20Ni80 alloy. Overall, the study provides an effective economical way for high-yield synthesis of nc Fe-Ni particles with tailored shape and subsequently magnetic properties for a specific technological application. Additionally, it adds a new morphology, highly branched wires, of distinctive magnetic behavior to the known morphologies of nc Fe-Ni particles.