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چکیده
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Fe3O4 magnetic nanoparticles (NPs) were synthesized via the chemical co-precipitation method and incorporated into a polyvinyl alcohol (PVA) matrix at various concentrations (1, 3, 5, and 7 wt.%). The structural, morphological, magnetic, and optical properties of the nanocomposites were systematically characterized using FTIR, FE-SEM, XRD, UV–vis spectroscopy, and vibrating sample magnetometry (VSM). FTIR analysis revealed that the incorporation of Fe3O4 NPs led to notable shifts in the O–H bending vibrational frequencies, suggesting the formation of new hydrogen bonds between the Fe3O4 surface and hydroxyl groups of PVA chains. These interactions potentially alter the overall hydrogen bonding network within the polymer matrix. XRD results showed a gradual decrease in the degree of crystallinity with increasing nanoparticle content, indicating good dispersion and disruption of the semi-crystalline PVA structure. FE-SEM images confirmed the uniform distribution of NPs with minor micro-crack formation, especially at lower doping levels due to weak matrix-filler interactions. VSM measurements demonstrated that the magnetic properties of PVA were significantly enhanced due to the stabilization of Fe3O4 NPs through hydrogen bonding, which also minimized NP agglomeration. UV–vis analysis showed increased optical absorption, a rise in the refractive index, and enhanced optical dielectric constants with increasing Fe3O4 concentration. Additionally, the optical bandgap energy decreased, while the linear (χ(1)) and third-order nonlinear (χ(³)) susceptibilities, along with the nonlinear refractive index (n2), were significantly improved. These results indicate that Fe3O4/PVA nanocomposites are promising materials for magnetic, optical, and optoelectronic applications.
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