Enhanced electromagnetic wave absorption performance of Ni–Zn ferrite through the added structural macroporosity

Abstract

Progressive utilization of wireless communications necessitates the use of electromagnetic wave absorber materials to assure a healthy environment for both devices and human beings by reducing the electromagnetic waves interference pollution. Nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4) ceramic foam was successfully fabricated using the sacrificial templating method to be utilized as a low-density electromagnetic wave absorber. Structural, morphological, magnetic, and electromagnetic wave absorption properties of the samples were studied as a function of intentional porosity percentage by using modern characterization techniques of X-ray diffraction, Raman spectroscopy, micro-XRF, scanning electron microscopy, magnetic flux (B–H) analyzer, and vector network analyzer. SEM micrographs confirmed the uniform distribution of porosity with a mean diameter size of 50 μm. Magnetic measurements showed magnetic flux saturation (Bs) in the range of 85–203 mT and hysteresis loss up to 119 J m−3 for the Ni–Zn ferrite porous ceramics. Electromagnetic evaluations of the reticular ferrites manifested 99% attenuation of the incident electromagnetic waves with minimum reflection losses (RL) of about −30.6 to −38.3 dB at optimum thicknesses of 3.5–4.9 mm and the effective absorption bandwidth at RL = −20 dB up to 2 GHz. The high electromagnetic wave absorption performance in the broad 1–18 GHz region was attributed to the contribution of intrinsic magnetic/dielectric loss mechanisms of the sintered nickel-zinc ferrite body, the synergic attenuation effects of the foamy structure, and the impedance matching characteristics as a result of converging the permeability and permittivity.

Keywords

• Porous ceramics
• Nickel zinc ferrite
• Electromagnetic wave absorber, Ceramic foam