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The electromagnetic pollution problem, particularly at microwave frequencies, poses a threat to not only sensitive technological gadgets but also to the health of humans. Therefore, there is a great need for lightweight and highly effective microwave-absorbing materials (MAMs). Here, we fabricated a hierarchical flower-like MoSe 2 structure and a rod-like MnFe 2 O 4 @MnO 2 architecture via a solvothermal method. Single-layer and bilayer samples were fabricated to study the microwave absorption feature. In single-layer samples, the flower-like MoSe 2 structure has better microwave absorption properties than the rod-like MnFe 2 O 4 @MnO 2 architecture. And in bilayer absorbing samples, a sample with a flower-like MoSe 2 structure as the top layer shows high absorption performance. Moreover, in bilayer samples, changes were made to the thickness of both layers to find the best parameters. An optimal bilayer sample has been achieved with a flower-like dielectric MoSe 2 structure as a top layer having a 1 mm thickness and magnetic MnFe 2 O 4 @MnO 2 as a bottom layer also with a 1 mm thickness; indicating that a strong absorption can only be attained by balancing dielectric loss and magnetic loss. Moreover, the optimal sample shows decent absorption with an effective absorption bandwidth (EAB) of 5.4 GHz (14.7–9.3 GHz) with a 1 mm thickness of each layer. The simulated results of the optimal sample have also been compared with experimental results. These results suggest a different approach for developing MAMs in the future. [ABSTRACT FROM AUTHOR]

Electromagnetic absorbent materials have received significant attention, recently, due to the growing concern about microwave contamination caused by widespread electronic devices. So, a lot of work has been done to develop advanced absorbing materials with excellent performance. Here, B i 2 S 3 decorated L a C o O 3 nanocomposite has been fabricated via a solvothermal method. To study the microwave absorption properties, L a C o O 3 @ B i 2 S 3 nanocomposites with 5, 15, 25, 35 and 40 wt% loadings were prepared. With optimal microwave absorption performance, a 35 wt% sample has decent minimum reflection loss (RL mini) with qualified frequency bandwidth (RL > 10 dB) covering nearly the whole X-band. Enhancements in microwave absorption efficiency of 35 wt% sample are ascribed to the highest dielectric loss, highest magnetic loss, maximum attenuation constant, as well as optimal impedance matching value. Furthermore, the optimal sample is tested via two measurement techniques; waveguide and free-space methods. A Comparison has been drawn between the variation of reflection loss measured by both methods. The free-space approach proves a good alternative measurement technique with contact-free and non-destructive benefits. Our findings may be useful in the design and fabrication of L a C o O 3 @ B i 2 S 3 nanocomposites for efficient microwave absorbers. [ABSTRACT FROM AUTHOR]

Composition and structural design play a very influential role in the microwave absorption (MA) manipulation of ferrite/carbon composites. Here, by carefully choosing the dimensionality of the bio-carbon materials, the interfacial geometries and MA properties of ferrite/bio-carbon composites have been controlled effectively. The one dimensional (1D), two dimensional (2D), and three dimensional (3D) biomass-based carbon materials decorated with ZnFe 2 O 4 (ZFO) particles were obtained respectively from carbon fibers (1D), tree leaves (2D), wheat straw (2D), peanut shell (3D) and orange peel (3D) by a simple two-step synthesis method. With increasing the bio-carbon's dimensionality from 1D, 2D to 3D, the ferrite/carbon composite's MA properties are promoted and the minimum reflection loss is enhanced from −9 dB to −45 dB. By changing the ZFO/3D-bio-carbon samples' thickness, a broad absorption range from 4 to 18 GHz can be covered. Moreover, the effective absorption bandwidth for ZFO/3D-bio-carbon can be modified up to 7.1 GHz, which covers the whole Ku band. These observations identified the important roles of the ferrite/carbon interface and dimensionality of carbon materials and provided an effective and low-cost route to design microwave absorption materials based on biomass-industrial waste composites. [ABSTRACT FROM AUTHOR]