Nano-porous carbon wrapped SiC nanowires with tunable dielectric properties for electromagnetic applications

Controllable Fabrication of SiC@C-Fe3O4 Hybrids and Their Excellent Electromagnetic Absorption Properties

“…It is easy to find that the relative intensity of Fe3O4 becomes more distinct with the increasing molar content of iron precursors (FeCl3•6H2O and FeCl2•4H2O). Moreover, a broad peak at 26.5°, corresponding to the (002) reflection of the carbon phase can also be detected for SCF samples, which is inferred as an amorphous carbon phase based on the previous work [27]. A similar phenomenon also occurs for some other carbon materials with solid crystalline characteristics or an amorphous solid state [28].…”

“…The nanowires are composed by four elements (C, Si, O, Fe) from the line scanning profiles, as shown in Figure 3d, which is in line with the results by EDS technique (Table S1). Moreover, the C line is broader compared with the Si element, confirming the core-shell structure of SiC@C. Simultaneously, the Fe and O lines cover nearly all ranges with weak fluctuations, inferring that a large quantity of Fe3O4 nanoparticles attach to the whole surface of SiC@C. Figure 3f shows the interface between SiC core and the carbon middle shell [27], and the interface between the carbon shell and Fe3O4 nanoparticles. It is apparent that β-SiC and the Fe3O4 phase possess crystal structures, featured with plane (111) and plane (311), respectively.…”

“…There is a middle layer, namely the carbon shell on the surface of SiC nw , which has a relatively better conductivity and helps to increase conductivity loss (Figure 7c) [34]. Moreover, the carbon shell between the SiC and Fe 3 O 4 phase possesses many pores (mesopores or macropores) demonstrated by previous work [27], implying that there are many defects that can cause the dipole polarization and Debye relaxations by breaking the balance of the charge distribution [35,36]. In addition, phase boundaries among the SiC nw core, the porous carbon shell, and the Fe 3 O 4 nanoparticles on the surface of carbon, possibly cause the surface charge redistribution and generate multiple interfacial polarization (Figure 7b).…”

“…SiC belongs to typical dielectric loss material for microwaves, while Fe 3 O 4 belongs to a magnetic material. In our previous work [27], it was found that the dielectric property of SiC nw was enhanced by surface carbonization, which led to the achievement of SiC@C. It is also inferred that the controllable inducement of magnetic Fe 3 O 4 nanoparticles may further change the dielectric properties [32,33]. It can be observed from Figure 5 that the magnetic tangent loss has a great increment for the SiC@C-Fe 3 O 4 hybrids in comparison with SiC nw , while the value of dielectric tangent loss for SiC nw and SCF samples stays at a similar level.…”

“…The pristine SiC nw materials (Diameter: 100~600 nm; Length: >100 µm; Density: 3.21 g/cm 3 ; Purity: ~98%) were purchased from XF Nano Materials Tech Co., Ltd. (Nanjing, China), whose chemical composition detected by X-ray spectrometer (EDS) technique is shown in Table S1. For the carbon-coated SiC nanowires (SiC@C), the specific synthesis process, detailed characteristics and EM absorption performances were described in our previous work [27]. However, it is noted that the furnace body condition is fixed to the temperature of 800 • C for 1h during surface carbonization of SiC nw .…”