Preparation, Characterization and Magnetic Properties of Fe-Ni Alloy/Ni-Ferrite Composite Nanofibers

Abstract

A series of Fe-Ni alloy/Ni-ferrite composite nanofibers with average diameters of 60~70 nm were successfully fabricated using electrospinning combined with the hydrogen-thermal reduction method. The thermal decomposition behavior of electrospun precursor nanofibers and crystal structures, phase compositions, morphologies and magnetic properties of the resultant products were characterized by means of thermogravimetric and differential thermal analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and vibrating sample magnetometer. It is found that both the preparation temperature of the pristine Ni-ferrite nanofibers and the reduction tem- perature have considerable influences on the phase compositions and magnetic properties of the corresponding reduction products. With increasing reduction temperature from 270 to 400 ℃ for the Ni-ferrite nanofibers prepared at 550 , ℃ the con- -1 , respectively. Compared to the pristine Ni-ferrite nanofibers, the prepared Fe-Ni alloy/Ni-ferrite composite nanofibers exhibit more excellent soft magnetic properties with much enhanced saturation magnetization due to introduction of Fe-Ni alloy phase. Furthermore, the composite nanofibers composed of three magnetic phases in crystallog- raphy show a good single-phase magnetic behavior, implying that these magnetic phases in composites are well exchange- coupled with each other. The observed changes in magnetic properties for the prepared composite nanofibers can be ex- plained on the basis of the differences in intrinsic magnetic properties between Fe-Ni alloy and Ni-ferrite phases and the changes in grain size, phase composition and magnetic interactions. These novel magnetic composite nanofibers have poten- tial application prospects in flexible magnets, sensing devices, catalysis, microwave absorption and electromagnetic interfer- ence (EMI) shielding. Keywords Ni-ferrite; Fe-Ni alloy; composite nanofibers; magnetic properties; electrospinning; hydrogen-thermal reduction