Synthesis of FeNi3 nanoparticles in benzyl alcohol and their electrical and magnetic properties

Pure and highly crystalline FeNi₃ alloy nanoparticles (NPs) were synthesized via sol–gel route with benzyl alcohol, using hydrazine as a reduction reagent without the usage of additional surfactant molecules nor further annealing processes. The structural studies revealed that the particle size is of ca. 200 nm, whose structure consisted on aggregation of small crystallites of about 13 nm. The magnetic properties of the as-synthesized NPs were similar to the bulk with a saturation magnetization of 95 emu g^?1. Moreover, the coercive field was ca. 50 G, exhibiting a M _r /M _s ratio of 0.03, indicative of soft ferromagnetism. The electrical transport in the temperature range 2–300 K exhibits a typical ferromagnetic metallic behaviour. Finally, similar FeNi₃ NPs were synthesized in EtOH/H₂O mixtures in the presence of sodium dodecyl sulphate molecules as surfactant for comparative purposes, exhibiting a typical half hard magnetic behaviour, highlighting the interest of the reported benzylic route.