“…Figure 9 depicts the matching thickness versus maximum RL and efficient bandwidth (RL > 10 dB) of the absorbers, as well as Fig. 10 represents a comparative diagram related to the maximum RL and efficient bandwidth (RL > 10 dB) of the reported results and this research 51 – 56 , 97 – 101 . Figure 8 Microwave absorption and efficient bandwidth of the samples at x and ku-band frequencies.…”
Section: Resultsmentioning
confidence: 89%
“… Figure 9 Matching thickness versus maximum RL and efficient bandwidth (RL > 10 dB) of the absorbers. Figure 10 Comparing the microwave absorbing properties of the carbon-based absorbers 51 – 56 , 97 – 101 . …”
Section: Resultsmentioning
confidence: 99%
“… Comparing the microwave absorbing properties of the carbon-based absorbers 51 – 56 , 97 – 101 . …”
Biomass-derived materials have recently received considerable attention as lightweight, low-cost, and green microwave absorbers. On the other hand, sulfide nanostructures due to their narrow band gaps have demonstrated significant microwave characteristics. In this research, carbon microtubes were fabricated using a biowaste and then functionalized by a novel complementary solvothermal and sonochemistry method. The functionalized carbon microtubes (FCMT) were ornamented by CuCo2S4 nanoparticles as a novel spinel sulfide microwave absorber. The prepared structures illustrated narrow energy band gap and deposition of the sulfide structures augmented the polarizability, desirable for dielectric loss and microwave attenuation. Eventually, the architected structures were blended by polyacrylonitrile (PAN) to estimate their microwave absorbing and antibacterial characteristics. The antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were scrupulously assessed. Noteworthy, the maximum reflection loss (RL) of the CuCo2S4/PAN with a thickness of 1.75 mm was 61.88 dB at 11.60 GHz, while the architected FCMT/PAN composite gained a broadband efficient bandwidth as wide as 7.91 GHz (RL > 10 dB) and 3.25 GHz (RL > 20 dB) with a thickness of 2.00 mm. More significantly, FCMT/CuCo2S4/PAN demonstrated an efficient bandwidth of 2.04 GHz (RL > 20 dB) with only 1.75 mm in thickness. Interestingly, FCMT/CuCo2S4/PAN and CuCo2S4/PAN composites demonstrated an electromagnetic interference shielding efficiency of more than 90 and 97% at the entire x and ku-band frequencies, respectively.
“…Figure 9 depicts the matching thickness versus maximum RL and efficient bandwidth (RL > 10 dB) of the absorbers, as well as Fig. 10 represents a comparative diagram related to the maximum RL and efficient bandwidth (RL > 10 dB) of the reported results and this research 51 – 56 , 97 – 101 . Figure 8 Microwave absorption and efficient bandwidth of the samples at x and ku-band frequencies.…”
Section: Resultsmentioning
confidence: 89%
“… Figure 9 Matching thickness versus maximum RL and efficient bandwidth (RL > 10 dB) of the absorbers. Figure 10 Comparing the microwave absorbing properties of the carbon-based absorbers 51 – 56 , 97 – 101 . …”
Section: Resultsmentioning
confidence: 99%
“… Comparing the microwave absorbing properties of the carbon-based absorbers 51 – 56 , 97 – 101 . …”
Biomass-derived materials have recently received considerable attention as lightweight, low-cost, and green microwave absorbers. On the other hand, sulfide nanostructures due to their narrow band gaps have demonstrated significant microwave characteristics. In this research, carbon microtubes were fabricated using a biowaste and then functionalized by a novel complementary solvothermal and sonochemistry method. The functionalized carbon microtubes (FCMT) were ornamented by CuCo2S4 nanoparticles as a novel spinel sulfide microwave absorber. The prepared structures illustrated narrow energy band gap and deposition of the sulfide structures augmented the polarizability, desirable for dielectric loss and microwave attenuation. Eventually, the architected structures were blended by polyacrylonitrile (PAN) to estimate their microwave absorbing and antibacterial characteristics. The antibacterial properties against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) were scrupulously assessed. Noteworthy, the maximum reflection loss (RL) of the CuCo2S4/PAN with a thickness of 1.75 mm was 61.88 dB at 11.60 GHz, while the architected FCMT/PAN composite gained a broadband efficient bandwidth as wide as 7.91 GHz (RL > 10 dB) and 3.25 GHz (RL > 20 dB) with a thickness of 2.00 mm. More significantly, FCMT/CuCo2S4/PAN demonstrated an efficient bandwidth of 2.04 GHz (RL > 20 dB) with only 1.75 mm in thickness. Interestingly, FCMT/CuCo2S4/PAN and CuCo2S4/PAN composites demonstrated an electromagnetic interference shielding efficiency of more than 90 and 97% at the entire x and ku-band frequencies, respectively.
“…Besides, numerous other superior microwave absorbers related to MnO 2 such as PANI/MnO 2 /CF, 23 NiFe 2 O 4 /MnO 2 , 24 carbonyl iron/MnO 2 (ref. 25) were also reported. Thus, it is signicant to develop a microwave absorber by using MnO 2 .…”
In this study, a novel hierarchical carbon fiber@cobalt ferrite@manganese dioxide (CF@CoFe2O4@MnO2) composite was facilely prepared via a sol–gel method and hydrothermal reaction.
“…The development of a microwave absorbing material (MAM) is directly related with the materials engineering to provide the current edge requirements of competitively growing civil and military fields. − The electromagnetic pollution caused by vast uses of telecommunication and electronic devices affects severally to the human health and also disturbs proper functioning of nearby electronic devices in the form of an electromagnetic interference (EMI). ,, The known potential of MAMs is to reduce the EMI pollutions, and hence, the investigations involving MAMs are now becoming a hotspot both in civil and military sectors. ,, Usually, in the military fields, the exploration of MAMs is focused in the X band ranging from 8.0–12.0 GHz frequency as RADAR interrogative devices are specially designed to operate in this range. ,, Concerning this, the aim of MAMs is to reduce the range detection, i.e., minimize the RADAR cross section . To achieve this, MAMs are typically coated on the target object, which consists of aircrafts, ships, etc.…”
In the present study, the milled carbon fiber (MCF) and conductive polyaniline (PANI) are impregnated in the epoxy matrix to synthesize a lightweight nanocomposite, providing efficient microwave absorption in the X band. The PANI 3D hollow spheres are uniquely synthesized by removing the polystyrene (PS) core structure of PS/PANI composites. The MCF and as-synthesized PANI hollow spheres are characterized by Raman spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The FESEM analysis confirmed the formation of 3D hollow PANI conductive spheres, which exhibited numerous porosity and high roughness on PANI sphere surfaces. The XRD revealed that the size reduction of carbon fibers down to the micro level resulted into more graphitic carbon. The MCF-and PANI-impregnated epoxy nanocomposites are evaluated by reflectivity measurements for their microwave absorption capabilities, exclusively in the X band. The correlation of the results shows that the ratio of MCF and PANI fillers in the epoxy matrix can be customized to obtain the desired microwave absorption performance of the synthesized nanocomposite. A maximum absorption value of −49.3 dB (99.998% absorption) as well as 1.7 GHz −10 dB effective bandwidth is achieved using a nanocomposite sample of 1.8 mm thickness comprising 4 wt % MCF and 1 wt % PANI filler loadings. The strong microwave absorption in the present situation for a very thin sample using just 5% of the total filler results into quite a lightweight composite, which basically originates from the electric/dipolar polarization in the interfacial polarization dominant in the micron length fibers and hollow 3D PANI spherical structures. The hollow 3D morphology here improves the impedance matching of the resulting nanocomposite sample due to multiple reflections and scattering of EM waves inside the structure, which substantially increases the reflection loss of EM waves in the specified frequency band. The novelty of this work lies in synthesizing the PANI/MCF-based filler for the first time and using it to develop a lightweight nanocomposite, which is found to be quite an efficient microwave absorber, especially for X band applications.
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