Synthesis and characterization of iron selenide-epoxy composites for enhanced optical, dielectric and EMI shielding applications

Fe₃Se₄, 4c - Fe₇Se₈ and 3c - Fe₇Se₈ nanoparticles were synthesized using the solid-state reaction method, which was then incorporated into bisphenol A-epichlorhydrin epoxy resin to form nano-epoxy composites. The optical properties were analyzed using UV–visible spectroscopy, revealing a reduction in the optical band gap of the nanocomposites compared to neat epoxy, indicating enhanced light absorption and potential applications in optoelectronic devices. Fourier transform infrared spectroscopy (FTIR) was used to investigate the interactions between the nanoparticles and the epoxy matrix. In the radio wave frequency range, an increase in the ε′ was observed for the nanocomposites, which was attributed to polarization effects introduced by the nanoparticles. Microwave dielectric properties of the nanocomposites were characterized using a vector network analyzer (VNA), which was further utilized to assess their electromagnetic interference (EMI) shielding effectiveness. This study highlights the stable dielectric constant at microwave frequency and the dominance of absorption over reflection across the X band with an efficiency of approximately 8 to 9 dB. The findings suggest that Fe-Se nanoparticle-doped epoxy composites are promising materials for applications requiring enhanced optical, dielectric and EMI shielding properties.