The novel Co-doped MoO₃ microwave absorber prepared by heat treatment

Abstract

A Co-doped α-MoO3 microwave absorber was prepared using by heat treatment technology. The oxygen vacancy, conductivity, and electromagnetic parameters of the material could be manipulated by changing the heat treatment temperature, and the microwave absorption mechanism was explored. XRD, Raman, SEM, XPS, and VNA were used to characterize the Co-doped α-MoO3 samples. The orthorhombic phases and scale-layer rod-like structure were observed to favor absorption via multiple transmission paths to EM waves. Notably, the material prepared by heat treatment at 500 °C exhibits a synergistic effect of magnetic and dielectric loss, due to its proper conductivity, rich interfaces and magnetism. The effective absorption bandwidth reaches 2.4 GHz .

Suppressed conductive loss of flower-like NiCo2O4-wrapped flaky FeSiAl for excellent low-frequency microwave absorption

“…To explore the effect of the introduced NiCo 2 O 4 on the EMW attenuation capability of flaky FeSiAl, we determined the frequency dependence of the dielectric loss tangents (tanδ e = ε ′′ /ε ′ ), magnetic loss tangents (tanδ m = µ ′′ /µ ′ ) and attenuation constants (γ) of the flaky FeSiAl and NiCo 2 O 4 @flaky FeSiAl (figure 10). The γ value can be calculated as follows [29,41]: Large tanδ e , tanδ m and γ values can be achieved in the flaky FeSiAl, in addition to the unchanged tanδ m value at the low-frequency range. This finding reveals that the surface coating of NiCo 2 O 4 weakened the EMW attenuation capability of the flaky FeSiAl.…”