Microwave absorption properties of core double-shell FeCo/C/BaTiO₃ nanocomposites.

Microwave absorption properties of core double-shell FeCo/C/(x)BaTiO₃ nanocomposites were investigated in the 1-18 GHz frequency range. High resolution transmission electron microscopy studies reveal the core double-shell type nanocomposite with FeCo nanoparticles as the center, while carbon and BaTiO₃ are the inside and the outside shells, respectively. Enhanced relative permittivity made the core double-shell FeCo/C/(x)BaTiO₃ nanocomposites with better electromagnetic impedance matching than that of a FeCo/C and BaTiO₃ mixture. Reflection loss (RL) values of FeCo/C/(20 wt%)BaTiO₃-paraffin composite are almost double those of the FeCo/C-paraffin composite at the absorbent thickness from 2 to 7.5 mm due to enhanced interfacial effects. The RL value of the FeCo/C/(20 wt%)BaTiO₃-paraffin composite is -41.7 dB at 11.3 GHz at the absorbent thickness of 2 mm and a broad absorption bandwidth of 5.1 GHz (RL values exceeding -10 dB) covers the 9.4-14.5 GHz frequency range.