Structural, dielectric, and magnetic properties of Sr0.7Cr0.3Fe12O19–polyvinyl alcohol nano-composites.

Nano-composites consisting of polyvinyl alcohol (PVA) immersed with Sr_0.7Cr_0.3Fe₁₂O₁₉ hexaferrites nanoparticles were successfully synthesized by two-step process. Nanoparticles (Sr_0.7Cr_0.3Fe₁₂O₁₉) were prepared by the sol–gel auto-combustion method and then embedded with polyvinyl alcohol matrix by the ultrasound in situ emulsion technique. The result indicates that the fabricated nanoparticles were homogeneously diffused in the matrix of PVA. Characterization of the synthesized material was done by the X-ray diffraction, Raman spectra and EDX analysis. The peaks of the XRD pattern become more intense with increasing the ferrite content in the polymer matrix which suggests that the crystallinity was improved with the addition of the ferrite content in the polymer matrix. Crystallite size and cell volume lie in the range of 34–59 nm and 688.83–693.82 nm, respectively. The magnetic field-dependent magnetic properties of the synthesized samples were inspected at room temperature by the vibrating sample magnetometry (VSM). The linearity of Ms, Hc, Mr values and shape of the hysteresis loop clearly indicate that the prepared ferrites nanoparticles were dispersed evenly within the polymer matrix. With the addition of ferrites in polymer composites, saturation magnetization, remanence, and coercivity were found to be enhanced. Saturation magnetization and remanent magnetization ranges from 6–42 emu/g and 4–22 emu/g, respectively, and magnetocrystalline anisotropy ranges from 3.7–5.6 (10⁵ erg/cm³). At low frequency, dielectric constant and dielectric loss are high with few relaxation peaks. Both the real and imaginary parts of permittivity demonstrate increasing trend with the addition of ferrite content in the polymer matrix. AC conductivity of the Ferrite–PVA nano-composites was found to be increased with the increase of frequency following the Joncher's law. The increasing behavior of dielectric parameters with increasing ferrite ratio in PVA is suitable for different applications, especially in energy storage devices. [ABSTRACT FROM AUTHOR]