Synthesis and characterization of Ag/Fe3O4 electromagnetic shielding particles

• Due to the decoration of silver nano-particles, the inorganic magnetic composite particle shows excellent dielectric loss in the almost whole test frequency range and good magnetic loss at 2 GHz to 5 GHz, especially the particle also has infrared reflection characteristic.
• The well-performed obstacle Ag/Fe3O4 particles will be expected to be used as electromagnetic shielding particles in multiband smoke agent to improve the IR and electromagnetic interference performance of the smoke screen.

Ag/Fe3O4 nano-composites are synthesized by electroless silver plating technique and characterized by X-ray diffraction, scanning/transmission electron microscope, magnetic measurement equipment and vector network analyzer. They show the silver layer coated on the surface of the particles successfully, and which can enhance the dielectricity and permeability properties of the ferromagnetic particles. The dielectric loss values of the composites are more than 1.0 in the almost whole test frequency range and the imaginary part of permeability of Ag/Fe3O4 is higher than real part in 2–5 GHz. The value of Hc is increased to 165.2 Oe due to the extended relaxation time of magnetic domain deflection of the magnetic powders which covered by silver layer. And the calculated microwave loss is more than 20 dB in the whole frequency range. As a result, the Ag/Fe3O4 nano-composites are expected to be used as electromagnetic shielding particle material in multiband smoke agent.