Nano nickel powder/conductive polymer absorbing material

The high density and low dielectric loss of nickel absorbers cannot meet the impedance matching requirements, which limits their wide application in the field of microwave absorption [77]. The core/shell nanostructured materials synthesized with dielectric materials are considered to be the future due to their ability to simultaneously attenuate microwave electrical and magnetic energy, enrich interface dipoles, and highlight natural resonanceElectromagnetic wave absorbing materialsA great candidate material. Ni/PANI and Ni/PS nanochains with core-shell structure were synthesized using liquid-phase chemistry method, and their electromagnetic properties were studied in detail in the frequency range of 1-18 GHz. The results show that Ni/PANI has a large impedance matching region in the X-band, with an effective absorption bandwidth of 4.5 GHz when the absorption layer thickness is less than 3mm. When the material thickness is 2.71mm, the minimum reflection loss can reach -51.16 dB, while untreated polyaniline only has an absorption peak of -4.87dB at 4 GHz.

Polymer shell induced interface dipole polarizationNi nanochain based absorbent materialThe dielectric modulation plays an important role, and compared with the Ni interface modified by polar free radicals, the protonated PANI shell enhances interface polarization and greatly improves dielectric attenuation through charge accumulation behavior at the core/shell interface. A ternary mixture was synthesized using a three-step synthesis method Ni@SnO2 @PPy, SnO2, and PPy uniformly encapsulate nano Ni particles. Core shell structure at a frequency of 5.6 GHz Ni@SnO2 @The electromagnetic properties of PPy (RLmin=-30.1 dB) are much better than those of nano Ni particles (RLmin=-10.75 dB) and Ni@SnO2 （RLmin=-13.8 dB）， This is mainly attributed to the improvement of impedance matching and the enhancement of interface effects. Advanced Institute of Technology composite materials have the advantages of thin thickness, strong absorption, and wide bandwidth, making them a promising microwave absorber.

3.2.3 Nano copper powder/conductive polymer absorbing material

takeConductive polymerComposite with magnetic nanoparticles, on the one hand, the surface effect of nanoparticles improves the magnetic properties of the system while enhancing the heat resistance and stability of the material; On the other hand, most of the matrix in the absorbing system is polymer, and polymer coated magnetic particles are more conducive to enhancing the dispersibility and compatibility of the absorbing agent. Advanced Institute Technology adjusts absorption properties by precipitating polypyrrole (PPy) onto a mixture of copper and two different six ferrites, combining dielectric and ferromagnetic properties in a beneficial way. Studied the microwave reflection loss of materials,
The results indicate that the minimum reflection loss of undoped ferrite is greater than -10 dB; The bandwidth of ferrite doped with copper particles with RL ≤ -10 dB is 2.75 GHz, and the RL is only -17 dB at a frequency of about 10.15 GHz. This means that the presence of copper is beneficial for adjusting the position of the matching frequency, improving the reflection loss of the absorbing material, and increasing the bandwidth; After coating PPy on ferrite and copper, the minimum reflection loss at a frequency of 10.8 GHz was tested to be -22 dB. The effective absorption bandwidth covers all X-bands starting from 9.6 GHz and extends to the Ku band. The core-shell structure formed by coating PPy on a mixture of copper and hexaferrite combines the different properties of each component, making the multifunctional microwave absorbing material have both magnetic and dielectric losses, while enhancing the interfacial polarization between particles to obtain the best microwave absorption characteristics.