Structural and magnetic properties of Ni/C core–shell nanofibers prepared by one step co-axial electrospinning method

Magnetic behavior of Fe3O4@C nanofibers by a facile co-axial electrospinning method

“…Also there exists a relation between diameter of the nanofibers with the coerecivity at 300 K and the trend goes like, increasing the coercivity with decreasing the fiber diameter. This may be explained as, by decreasing the diameter the surface to volume ratio increases, which may create surface anisotropy energy and that phenomenon required high coerecivity [17,34,35]. Also, here we observed that decreasing the temperature from 300 to 5 K leads to an increase in Hc value.…”

“…The maximum value of saturation magnetization (Ms) calculated for Fe15@C is 11.9 emu g −1 , 13.3 emu g −1 , and 13.4 emu g −1 at 300 K, 100 K, and 5 K respectively. The calculated Ms value is low as compare to bulk Fe 3 O 4 (92 emu g −1 ) due to the contribution of magnetically inactive carbon shell [17,30]. Here, as we increase the Fe 3 O 4 content the Ms value gradually increases but for Fe20@C it is nearly equal to the previous composition sample for all defined temperatures.…”

“…Also, here we observed that decreasing the temperature from 300 to 5 K leads to an increase in Hc value. This may be due to the freezing of spin magnetic moment while cooling [17]. Therefore, the open hysteresis loop and the non-zero value of coerecivity and remanent magnetization suggested the ferromagnetic behavior of the samples at 300, 100, and 5 K [36].…”

“…Along with the above solution, a series of solutions were prepared following the above procedure and by varying the ferric nitrate solution concentration (10 wt%, 15 wt%, and 20 wt%) and labeled them as Fe10@C, Fe15@C, and Fe20@C respectively. Here the amount of polymer, metal salt, and solvent taken, was calculated based on our previous work [17]. The two solutions were transferred into two different 5 ml syringes, which are fitted with syringe pumps 1 and 2.…”

“…Owing to many potential applications of magnetic material-carbon nanofibers, wellarranged, structured fibers are required, which may control the fiber degradation, size, shape, etc. Hence to produce polymer nanofibers, researchers are using different methods like catalytic chemical vapor deposition [16], electrospinning/co-axial electrospinning [17], self-assembly polymerization [18], templating [19], and phase separation [20]. Among these methods, co-axial electrospinning is one of the methods which is having the potential to be upscaled for large-scale production and to produce polymer nanofibers as well as the polymer blend composite nanofibers having the core-shell structure [21].…”