Nature of Electromagnetic-Transparent SiO₂ Shell in Hybrid Nanostructure Enhancing Electromagnetic Attenuation

Abstract

The understanding of the structure−activity relationship can help us design desired functional materials. SiO 2 shell is widely used as a physicochemical inert layer to protect materials from corrosion or oxidization. But, in electromagnetic (EM) absorption studies, silica shell, supposed to be EM transparent, has been found to significantly influence the EM absorption performance. Here, we studied the microstructure, EM parameters, and electronic structure of silica shell coated SiC/Co (SiC/Co@SiO 2 ) nanowires to figure out the nature of silica shell influencing on their EM absorption. Xray absorption near-edge structures on Co L 3,2 -edge and O K-edge analysis confirm that silica links with Co by Si−O−Co bonds. Electron transfer takes place between silica and Co, which leads to formation of gradient ε field within silica and more incident EM wave entering into the absorbers. Generating significant interfacial polarization, the silica shell improves the EM absorption performance. The present research offers a novel insight on the functional role of silica shell.

Electromagnetic wave absorption of silicon carbide based materials

“…As a result, the carbon coated Co-SiC nanocomposites exhibited a high EM absorption performance with a broad absorption bandwidth. Liang 85 synthesized SiC/Co/SiO 2 material of multi-shell structure with a broad absorption bandwidth from 9.1 to 18 GHz (R L < À10 dB). The SiO 2 shell introduced charge transfer between SiO 2 and Co to achieve the impedance matching, resulting in promotion of the incident EM waves entering into the absorber.…”

Fabrication of novel silicon carbide‐based nanomaterials with unique hydrophobicity and microwave absorption property

“…However, due to poor dielectric properties aroused by single polarization, the weak MA capacity of SiC‐based materials greatly restricts their practical applications 9,17 . Therefore, a lot of efforts have been done in the past decades on the methods of introducing more multiple polarizations into SiC‐based materials to adjust their dielectric or magnetic properties so as to enhance their MA performance 17‐19 . For instance, Liang et al found that the doping of cobalt into SiC nanowires could enhance the magnetic loss of SiC nanowires, leading to the improvement of their MA performance.…”

“…In addition, Liang and his colleagues demonstrated that after coating a layer of SiO 2 on SiC/Co nanowires, the MA performance of the as‐obtained products were further improved with an effective absorption bandwidth (RL < −10 dB) extended to 8.9 GHz. This improved MA performance could be attributed to the transfer of charge at the core‐shell interface 19 . Hence, if the element doping and heterostructure construction are combined to modify SiC, it is predictable that the as‐obtained SiC materials will exhibit improved MA properties.…”

Investigation of Electromagnetic Interference Shielding Effectiveness of CZ Grown Ge Optical Windows

“…EMI shielding is necessary for lots of electrical–electronic equipment to prevent undesirable interference effects caused by electromagnetic waves. For this reason, EMI shielding performance of a number of popular materials such as carbon shell coated SiC (SiC@C), SiC/Co, graphene, silica shell coated SiC/Co (SiC/Co@SiO 2 ), reduced graphene oxides (r‐GOs), silica coated on carbon fiber (CF/SiO 2 ), and SiC foam has been evaluated in the literature.…”