Abstract
Magnetic iron oxide nanoparticles (Fe3O4) can be dispersed in a supporting material so that the composite can better respond to electromagnetic fields, absorbing a part of their energy. In the discussion here proposed, therefore, we will consider the role of these nanoparticles in the applications for electromagnetic interference (EMI) shielding. Inserted in intrinsically conducting polymers (ICPs) for instance, the nanoparticles are increasing EMI shielding effectiveness of polymer, producing light weight "absorption-type" shields, which are specifically relevant for absorbing microwaves. Composite materials, based on Fe3O4 nanoparticles with polypyrrole or polyaniline, will be considered in detail. Other materials, such as the recent biochar-based composites, will be discussed too.