X-Band Microwave Absorption in Nd³⁺-Substituted Mg–Cd Spinel Ferrites Synthesized Under Microwave Sintering

The electromagnetic parameters and microwave-absorbing properties of Nd
³⁺
-substituted Mg-Cd spinel ferrites with the chemical formula Mg
_x
Cd
_1-x
Nd
_0.03
Fe
_1.97
O
₄
(where x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) were investigated using vector network analyzer (VNA) in conjunction with the material measurement software. The permittivity of all the ferrites follows the usual dispersion behavior in the microwave frequency range. The behavior of ac conductivity and dielectric losses with frequency for various Mg content is quite similar. The variations in permeability with frequency for compositions with x = 0.4, 0.6, and 1 in the frequency range of 10-12.4 GHz obeys Snoek's law. The peaks observed in the magnetic loss tangent spectra may be due to spin rotation created in the ferrites. With an increase in magnesium content, the reflection loss peak gets deepened, signifying the increased improvement in the absorption properties. Thus, it can be stated that Mg-substituted Cd-Nd ferrites have better performance when compared with pure Cd-Nd ferrite, proposing it to be a suitable material for electromagnetic shielding applications in the X-band.