Ning Shao,Juan Li,Shenglei Che,Jingwu Zheng,Liang Qiao,Yao Ying,Jing Yu,Wangchang Li
The L -band and S-band electromagnetic waves are widely utilized in radar and satellite communications. This paper reports the successful synthesis of 85.8% content Ba 3 Co 2 Fe 24 O 41 (Co 2 Z) at a relatively low temperature of 1150 °C using the solid-phase method with BaFe 12 O 19 (BaM) and Ba 2 Co 2 Fe 12 O 22 (Co 2 Y) as precursors. The Co 2 Z samples were confirmed to have been successfully synthesized using X-ray diffraction (XRD) and thermogravimetry/differential scanning calorimetry (TG-DSC) spectra. Scanning electron microscopy (SEM) images revealed that the sintered samples exhibited large grains (>10 µm). Vibrating-sample magnetometry (VSM) data indicated that the synthesized Co 2 Z samples possessed distinct soft magnetic properties . X-ray photoelectron spectroscopy (XPS) results showed that the Fe 3+ content decreased with the increase in synthesis temperature. The samples synthesized at 1110 °C − 1280 °C had a permeability of 10–20, a cut-off frequency of approximately 1 GHz, and a dielectric constant of 10–30. When the thickness of the sample synthesized at 1150 °C was 3.9 mm, the frequency range of the reflection loss (RL)< −10 dB was 2.55 GHz (0.98–3.53 GHz), with 1.77 GHz as the center frequency, and RLmin was − 57.8 dB. This observation indicates that the effective absorption bandwidth of the samples covers the entire L and S bands, which significantly satisfies practical applications within the military and civilian sectors.
The problem of microwave pollution becomes more serious with the widespread popularity of electronic equipment; the development of microwave absorption materials has assumed critical importance. However, most reported carbon-based microwave absorption materials have no obvious absorption performance in 2–4 GHz (S band), which seriously limits their application. In this work, Ni(OH)2-coated peach pit carbon [Ni(OH)2/C1] is prepared by simple precipitation to achieve a minimum reflection loss (RL) value of −46.2 dB (5.6 mm, at 2.9 GHz) and absorption band cover 2.54–4 GHz in the thickness range of 3.7–6 mm in the S-band. In addition, Ni(OH)2/C1 achieved an RLmin value of −58.05 dB (2.7 mm, at 7.68 GHz) and maximum effective absorption bandwidth (EAB) of 3.95 GHz in the range 2–18 GHz. Our work provides new insights into the microwave absorption in low frequencies and expands the application range and scenarios of carbon-based materials.
Flexible and wearable electromagnetic interference (EMI) shielding material is one of the current research focuses in the field of EMI shielding. In this work, for the first time, WS 2 -carbon fiber (WS 2 -CF) composites are synthesized by implanting WS 2 , which has a multiphase structure and a large number of defects, onto the surface of carbon fiber (CF) by using a simple one-step hydrothermal method, and are applied to protect electronic devices from EMI. It is found that the EMI shielding performance of WS 2 -CF is significantly improved, especially for those at S and C-bands. At 2 GHz, the EMI shielding efficiency could reach 36.0 dB at a typical thickness of 3.00 mm of the composite, which is much better than that of pure CF (25.5 dB). Besides paving a novel avenue to optimize the electromagnetic shielding performance of flexible and wearable CF-based EMI shielding materials, which have great potential in the practical application for EMI shielding, this work provides a new paradigm for the design and synthesis of EMI shielding materials which have a broad application prospect.
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