Synthesis and investigation of polyvinylpyrrolidone-polymer content on magnetic and electromagnetic properties of electrospun BiFeO3, SrFe12O19, α-Fe2O3 nanostructures

A one-pot electrospinning technique was employed to synthesize polyvinylpyrrolidone (PVP)-based nanofibers containing bismuth ferrite (BiFeO3), strontium hexaferrite (SrFe12O19), and hematite (alpha-Fe2O3). The influence of PVP polymer concentration on structural properties revealed the formation of pure phases in all samples, except for BiFeO3 nanofibers, which contained an impurity Bi2Fe4O9 phase. Field-emission scanning electron microscope images showed that higher PVP concentrations resulted in longer, thicker nanofiber chains for all samples. Vibrating sample magnetometer analysis indicated that SrFe12O19 nanofibers exhibited strong ferrimagnetic properties with high saturation magnetization (60 emu g(-1)) and coercivity (5000 Oe), while the other samples displayed weaker magnetic properties. To address the fragility of nanofibers produced via the one-pot method, the highest PVP concentration nanofibers were incorporated into low and high concentrations of paraffin matrices. Electromagnetic testing showed that paraffin concentration significantly increased the real part of electrical permittivity for BiFeO3 nanofibers (from similar to 2 to similar to 4.5) compared to other compositions (similar to 2 to similar to 3). Impedance results revealed that BiFeO3 nanofibers had the lowest resistance and likely higher reflectivity. Lastly, the real permittivity of nanofibers decreased with increasing frequency, aligning with Koop's dielectric relaxation theory.