Phosphate Ceramics with Silver Nanoparticles for Electromagnetic Shielding Applications

Abstract

Ceramic composites with nanoparticles are intensively investigated due to their unique thermal, mechanic and electromagnetic properties. In this work, dielectric properties of phosphate ceramics with round silver nanoparticles of various sizes were studied in the wide frequency range of 20 Hz–40 GHz for microwave shielding applications. The percolation threshold in ceramics is close to 30 wt.% of Ag nanoparticles content and it is higher for bigger-sized nanoparticles. The microwave complex dielectric permittivity of ceramics above the percolation threshold is rather high (ε′ = 10 and ε″ = 10 at 30 GHz for ceramics with 50 wt.% inclusions of 30–50 nm size, it corresponds to almost 61% absorption of 2 mm-thickness plate) therefore these ceramics are suitable for microwave shielding applications. Moreover, the microwave absorption is bigger for ceramics with a larger concentration of fillers. In addition, it was demonstrated that the electrical transport in ceramics is thermally activated above room temperature and the potential barrier is almost independent of the concentration of nanoparticles. At very low temperature, the electrical transport in ceramics can be related to electron tunneling.

Electrical Resistivity and Microwave Properties of Carbon Fiber Felt Composites

“…It can be concluded that the absorption of some of these composite structures is quite high, for example, that of the RC X sample at 35 GHz is 55%. It is comparable to the best absorption of ceramics with SiC or Ag nanoinclusions, or hybrid carbon magnetic/carbon nanostructures [ 26 , 28 , 29 , 30 , 31 , 32 ]. Measurements in different directions reveal strong anisotropy of the electromagnetic response.…”

Investigation of the Effect of PbO Doping on Telluride Glass Ceramics as a Potential Material for Gamma Radiation Shielding

“…Also, important characteristics in shielding materials are the parameters of resistance to external influences, including mechanical or long-term radiation exposure, which has a cumulative effect. All this, despite the large number of studies in this area, requires new research and experimental confirmation of the efficiency of shielding of new types of materials depending on their composition and applications [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”