Synthesis and electromagnetic wave absorption performances of a novel (Mo0.25Cr0.25Ti0.25V0.25)3AlC2 high-entropy MAX phase

Preparation and properties of lightweight, conformal, and load‐bearing TiC/Si3N4 absorbing composites by gel casting

“…As a result, the dielectric loss is increased by the polarization relaxation process caused by the motion hysteresis of the dipole 44,49 . C is interfacial polarization, which occurs at the interface of amorphous carbon on the surface of TiC particles, Si 3 N 4 particles, and TiC particles when EM waves are incident, leading to interfacial polarization relaxation 32 . D is defect polarization, which occurs at the amorphous phase defects of amorphous carbon on the surface of particles 4 .…”

“…Secondly, the inner circle cutter was used to process the samples into 22.80 mm*10.10 mm*3.4 mm and 15.75 mm*7.85 mm*3.4 mm small pieces to test the dielectric parameters of the X band and P band by a vector network analyzer (E5071C) respectively. Finally, according to the transmission line theory, the reflection loss (RL) curves with different thicknesses were calculated by the following equations 10,30–32 : $$$$\begin{equation}{Z_0} = \sqrt {\frac{{{\mu _0}}}{{{\varepsilon _0}}}} \;\end{equation}$$$$ $$$$\begin{equation}{Z_{in}} = {Z_0}\;\sqrt {\frac{{{\mu _r}}}{{{\varepsilon _r}}}} \tan h\left( {\frac{{2\pi jfd}}{c}\sqrt {{\mu _r}{\varepsilon _r}} } \right)\end{equation}$$$$ $$$$\begin{equation} RL = 20\log \left| {\frac{{{Z_{in}} - {Z_0}}}{{{Z_{in}} + {Z_0}}}} \right|\end{equation}$$$$where Z 0 and $${Z_{in}}$$ are input impedances of air and the absorber, respectively. μ 0 and ε 0 are the permeability and permittivity of the vacuum.…”

“…Secondly, the inner circle cutter was used to process the samples into 22.80 mm*10.10 mm*3.4 mm and 15.75 mm*7.85 mm*3.4 mm small pieces to test the dielectric parameters of the X band and P band by a vector network analyzer (E5071C) respectively. Finally, according to the transmission line theory, the reflection loss (RL) curves with different thicknesses were calculated by the following equations 10,[30][31][32] :…”

“…44,49 C is interfacial polarization, which occurs at the interface of amorphous carbon on the surface of TiC particles, Si 3 N 4 particles, and TiC particles when EM waves are incident, leading to interfacial polarization relaxation. 32 D is defect polarization, which occurs at the amorphous phase defects of amorphous carbon on the surface of particles. 4 Therefore, the loss mechanisms of the prepared composites to electromagnetic waves are a combination of conductivity loss, multiple reflections and scattering, interfacial polarization, and defect polarization.…”

Multiprincipal Element M2FeC (M = Ti,V,Nb,Ta,Zr) MAX Phases with Synergistic Effect of Dielectric and Magnetic Loss

“…Moreover, high entropy (Mo 0.25 Cr 0.25 Ti 0.25 V 0.25 ) 3 AlC 2 MAX phase kept excellent EM wave absorption even after high‐temperature oxidation treatment. [ 10 ] Those above work indicated that the EM microwave absorption performance of MAX phases can be adjusted by tuning the composition elements of transition metals. In addition to dielectric loss, magnetic loss is also a way to enhance the electromagnetic attenuation capability of electromagnetic absorbers.…”