Constructing uniform Fe3O4@C@MnO2 microspheres with yolk-shell interior toward enhancement in microwave absorption

Polyimide-derived porous carbon/Co particle-based composites for high-performance microwave absorption

“…Further, according to the quarter-wavelength cancellation model, it is known that at a proper thickness, the EMWs from the air–absorber interface ( E 1 ) and absorber–metal interface ( E 3 ) are out of phase by 180°, leading to their extinction at the air–absorber interface. Thus, minimal reflection can be achieved at a certain EMW frequency ( f m , frequency related to the minimum RL value) if the thickness ( t m ) of the absorber composite satisfies the following matching equation: 35 …”

In Situ Reduced Multi-Core Yolk–Shell Co@C Nanospheres for Broadband Microwave Absorption

“…Based on the complex permittivity and complex permeability of MAM, the reflection loss (RL) can be calculated by the transmission line theory. The calculation method is shown as follows [ 58 , 59 ]: where Z in represents the input impedance of the material, and the calculation formula is as follows: where c represents the speed of light in free space, f represents the frequency of electromagnetic waves, and d represents the thickness of the absorber. Figure 6 shows the three-dimensional diagrams and contour diagrams of the RL values of Co 3 O 4 , S1, S2 and S3 in the frequency range of 2–18 GHz and d in the range of 1–9 mm.…”

Facile fabrication of exfoliated g-C3N4/MWCNTs/Fe3O4 ternary composites with multi-component functional synergy for high-performance microwave absorption

“…In addition, introducing non-magnetic dielectric materials into carbon magnetic materials can optimize the impedance matching and enhance the polarization loss, such as dipole polarization and interfacial polarization, which facilitate a widening bandwidth. Inorganic semiconductor materials with low dielectric constants, such as TiO 2 , 15 MnO 2 , 16 CuS, 17 MnO, 18 ZnO, 19 and Si 3 N 4 , 20 are often added to composites to regulate their dielectric characteristics. However, they are often limited by complex synthetic processes and demanding structural modification conditions.…”