Abstract
In recent decades, to reduce electromagnetic pollution, scientists focus on finding new microwave absorbers with effective performance, thin thickness, and broad bandwidth. In this work, the nanoparticles of NiFe2O4, X-doped g-C3N4 (M = S, P, and O), and MTiO3 (M = Fe, Mg, and Zn) were successfully synthesized using co-precipitation, specific heat program, and semi-wet sol–gel methods, respectively. The synthesized nanoparticles were utilized as absorption agents and polyester resin as the matrix. Morphology, particle size, crystal structure, and chemical composition of the prepared nanocomposites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and energy dispersive X-Ray analysis (EDX), respectively. The microwave absorption performance of the coatings was also investigated by a vector network analyzer (VNA). Moreover, the effect of different parameters on the performance of absorbent coatings was studied by the Taguchi method and optimized to achieve an optimal absorbent. The results showed that the optimal nanocomposite has the reflectance loss (RL) less than − 30 dB (equal to absorption > 99%) at a high-frequency range (8–12 GHz) and 1 mm thickness. Furthermore, the addition of such novel nanoparticles to absorbents resulted in high values of attenuation constant (more than 200 dB/m) at the X-band. Therefore, the polyester coating filled with ZnTiO3, O-doped g-C3N4, and NiFe2O4 nanofillers can be considered a high-efficiency and low-density absorber.
Highlights
In recent decades, to reduce electromagnetic pollution, scientists focus on finding new microwave absorbers with effective performance, thin thickness, and broad bandwidth
This X-ray diffractometer (XRD) pattern was well-matched with the JCPDS standard file No 10-0325, which confirm the formation of the single phase of iron oxide with the cubic spinel structure
Based on the results found from the ANOVA table, the optimum sample includes ZnTiO3, O-gC3N4, NiFe2O4, the 2:1 weight ratio for MTiO3:NiFe2O4, and the 1:2 weight ratio for MTiO3/NiFe2O4: X-doped g-C3N4
Summary
To reduce electromagnetic pollution, scientists focus on finding new microwave absorbers with effective performance, thin thickness, and broad bandwidth. The nanoparticles of nickel ferrite (NiFe2O4) with the soft spinel ferrite structure have attracted the attention of many researchers owing to their excellent chemical stability, good thermal stability, modest saturation magnetization, availability, lightweight, and high electrical resistivity. Conductor fillers, microwave dielectric materials, are widely used in the absorbers to lose electromagnetic energy, such as conductive polymers, graphite, CNT, etc Among these materials, the graphitic carbon nitride (g-C3N4) has attracted the attention of many researchers as a nonmetallic conductive material due to its unique properties such as high dielectric constant, excellent conductivity, and high specific area. The g-C3N4 conductivity increases by inserting phosphorus, oxygen, and sulfur atoms into the g-C3N4 lattice structure instead of carbon atoms, which may be due to rising electron motion[16,26,27]
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