Fabrication of a Low-Coercivity, Large-Magnetoresistance PVA/Fe/Co/Ni Nanofiber Composite Using an Electrospinning Technique and Its Characterization.

A nanofiber composite is a unique engineered material, which can impart new physical, chemical, and electrical properties. Among existing polymer composites, the metallic nanofiber composite has a significant role in biomedical applications. In this study, a metallic nanofiber composite was fabricated using poly vinyl alcohol [PVA-(C₂H₄O)n] reinforced with ferric nitrate [Fe(NO₃)₃·9H₂O], cobalt nitrate [Co(NO₃)₂·6H₂O], and nickel acetate [C₄H6NiO₄·4H₂O] using a low-cost electrospinning process. The process parameters were optimized for fabricating uniform, bead-free, and substratefree fibers. The morphological features of the composite were evaluated using a scanning electron microscope (SEM). Hysteresis of the heat-treated composite was studied using a vibrating sample magnetometer (VSM). This study showed that the composite behaved as a ferromagnetic (intermediate) material with coercivity in the range 318-671 G for different wt.% of nickel. Pellets (8-mm diameter and 250-μm thickness) of this composite changed the resistance by 18% when dispensed in a magnetic field of 1200 G at an ambient temperature. Based on a thermogravimetric analysis, the thermal stability and magnetoresistance property showed that the fabricated composite was suitable for developing a highly sensitive magnetic sensor, which could be used in bio-sensing applications.