Electrospun, Oriented, Ferromagnetic Ni1-xFex Nanofibers

Abstract

Electrospinning has been used to fabricate ferromagnetic Ni_0.47Fe_0.53 nanofiber mats that were composed of individual, orientated Ni_0.47Fe_0.53 nanofibers. The key steps were processing a polyvinylpyrrolidone nanofiber template containing ferric nitrate and nickel acetate metal precursors in Ar at 300°C and then 95% Ar: 5% H₂ at 600°C. The Ni_0.47Fe_0.53 fibers were nanostructured and contained Ni_0.47Fe_0.53 nanocrystals with average diameters of ~14 nm. The Ni_0.47Fe_0.53 ferromagnetic mats had a high saturation magnetic moment per formula unit that was comparable to those reported in other studies of nanostructured Ni_1-x Fe _x . There is a small spin-disordered fraction that is typically seen in nanoscale ferromagnets and is likely to be caused by the surface of the nanofibers. There was an additional magnetic contribution that could possibly stem from a small Fe_1-z Ni _z O phase fraction surrounding the fibers. The coercivity was found to be enhanced when compared with the bulk material.