W-type hexaferrite nanoparticles: A consideration for microwave attenuation at wide frequency band of 0.5–10 GHz

The static and dynamic magnetic properties of W-type hexaferrites are tuned to meet the requirements of wide band frequencies for attenuation of electromagnetic interference and microwave absorptions purposes. For this purpose, the W-type hexaferrite of entirely new composition of BaCoZnFe16−2yAlyCeyO27 (y = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) has been synthesized by the chemical co-precipitation. The material is characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The complex permittivity (ɛr = ɛ′ − jɛ″) and permeability (μr = μ′ − jμ″) spectra are determined using Vector Network Analyzer (VNA) in a range from 0.5 GHz to 10 GHz. During this study, it is noticeable that the Al3+ and Ce3+ ions have considerable effect on the shape of the nanoparticles. Samples having Al–Ce contents y = 0.2 and y = 0.4 showed large values for magnetization (70.5 emu/g) and remanent magnetization (32.9 emu/g). In addition, more than 99% absorption (>−20 dB) is noted for this sample composition. Based on these results it is concluded that the microwave absorption characteristics of these compounds can be tuned for the required frequency by varying the thickness of the absorber. Due to this reason, potential employment of the synthesized nanoparticles for absorption of electromagnetic radiations at wide frequency band of 0.5–10 GHz has been proposed.

Dependence of the reflection loss (RL) on thickness (tm) of the absorber for sample BaCoZnFe15.6Al0.2Ce0.2O27 (y = 0.2).Figure optionsDownload as PowerPoint slideHighlights
► Doping of Al3+ and Ce3+ on iron site in BaCoZnFe16O27 are found to have a prominent effect on shape of the particles, magnetic and absorption characteristics.
► The room temperature magnetization is improved up to 70 emu/g, the same is the case for remanent magnetization (32.9 emu/g) and coercivity (1.55 kOe).
► More than 99% of microwave absorption is achieved for some samples at optimum thickness of the absorber which make them suitable for electromagnetic interference attenuation and as radar absorbing materials.
► Variations of microwave absorption characteristics with the substitution of Al3+ and Ce3+ ions allow the possibility of material design for specific purposes by only varying the thickness of the absorber materials.