Microwave Absorption Properties Of Nanoparticles Research Articles

Correlation Between Structural Features and Microwave Analysis of Substituted Sr-Co2Y Ceramic Nanoparticles

In this study, Y-type strontium hexagonal ferrite (Sr2Co2Fe12o22) and Sr2Co2Fe12−y/2Al y/2o22 (where y = 0.0–3.0 in a step of 0.5) nanoparticles were prepared by a chemical co-precipitation method. Synthesis time and temperature were varied from 1 to 3 h and 800 to 1000 ∘C, respectively. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), vibration sample magnetometer (VSM), and vector network analyzer (VNA) were employed to study the structural, magnetic, and microwave absorption properties of nanoparticles. According to the results, the optimum condition for synthesize of Y-type Sr-hexaferrite was 900 ∘C at 1 h. The FE-SEM results showed that the particle size increases with increasing in the sintering temperature and also the morphology of particles is slowly twisted from a plate like hexagon to a complex polyhedron shapes. The coercivity has declined from 1327 to 153 Oe and saturation magnetization initially declined and then increased after the formation of Y-type Sr-hexaferrite phase. FE-SEM results for substitution samples showed that the particle size increased with an increase in Al 3+ ion. The maximum reflection loss of substituted Sr-hexaferrites reached −30.7 dB at a frequency of 11.3 GHz and a bandwidth of 3.3 GHz (RL >−10 dB). The obtained results shown that the suggested composites can be introduced as electromagnetic wave absorbers at gigahertz frequency range.

Magnetic and enhanced microwave absorption properties of nanoparticles of Li0.32Zn0.26Cu0.1Fe2.32O4 encapsulated in carbon nanotubes

Nanoparticles of Cu2+ doped Li–Zn ferrite (Li0.32Zn0.26Cu0.1Fe2.32O4, LZCF) was prepared by sol–gel method. The prepared nanoparticles were encapsulated by a non-magnetic matrix of multi-walled carbon nanotubes (CNT). The formation of pure crystallographic phase, particle size etc. of each sample was determined from X-ray diffractograms and these results are in good agreement with those obtained from the high-resolution transmission electron microscopy. The results of static and dynamic magnetic measurements suggest the modulation of magnetic behavior of LZCF nanoparticles by coating with CNT. The reflection loss of each sample was measured in the microwave frequency range of 8–18GHz. Interestingly, the microwave absorption of LZCF nanoparticles was drastically enhanced after encapsulation with CNT.