Polycarbonate Composites Containing Carbon Encapsulated ``Brick-Like'' Fe3O4 Nanoparticles as Efficient Microwave Absorbers with a Large Bandwidth

This study demonstrates lightweight microwave absorber materials designed using polycarbonate (PC) nanocomposites containing multiwall carbon nanotubes (MWNTs) and ``brick-like'' lossy magnetic ferrite (Fe3O4) nanoparticles encapsulated with carbon (Fe3O4@C). The designed nanocomposites manifested in exceptional microwave attenuation through absorption (89%). The unique strategy, of encapsulating ferrites with C, adopted here prevents the disruption of conducting pathway facilitated through the network of MWNTs and overcomes the eddy current effects. In addition, this strategy further led to improved dispersion of ferrites in PC matrix which rather agglomerates during processing. Unlike classical electromagnetic interference (EMI) shielding materials, the PC nanocomposites containing MWNTs and Fe3O4@C resulted in exceptional microwave attenuation in a broad frequency range and mostly through ab-sorption. The absorption ability of these nanocomposites was further assessed by evaluating the reflection loss (RL). For instance, PC nanocomposites containing MWNTs and Fe3O4@C nanoparticles depicted in an exceptional RL of -41.3 dB at 17.7 GHz and with a remarkable bandwidth of 4.4 GHz for a thickness of 1 mm. Unlike previous studies where RL was improved by sacrificing dielectric losses, herein, the adopted strategy enhances both dielectric losses facilitating in enhanced total shielding effectiveness (SET) and RL through suitable impedance matching. This further result in excellent absorption. Therefore, this study provides comprehensive understanding about tailoring the complex microwave properties of the polymer nanocomposites in order to achieve enhanced microwave absorption