High Dielectric Fe₃O₄ and Fe₂O₃ Nanoparticles Deposited on Graphite Nanosheets for Electromagnetic Wave Absorption

Abstract

Fe3O4/graphite nanosheets (GNs) nanocomposites were obtained by the solvothermal method and calcined in an air environment to obtain Fe2O3/GNs nanocomposites. The phase and microstructure can clearly demonstrate the evolution process of Fe3O4/GNs to Fe2O3/GNs nanocomposites. The Fe3O4/GNs nanocomposites will be converted from Fe3O4 to Fe2O3 during calcination to form nanoparticles. When the calcination temperature is 250 °C, the glucose on the surface of the S-250 sample begins to carbonize, resulting in an excellent reflection loss value of −66.593 dB when the thickness is 2.8 mm and the effective absorption bandwidth is 3.28 GHz. The mutual contact between the nanoparticles and GNs makes the composites produce more interface/dipole polarization and better impedance matching. Calcination converts Fe3O4/GNs to Fe2O3/GNs, which is a high-performance design with a unique structure and has potential applications in the field of electromagnetic-wave absorption.

Heterostructure design of 3D hydrangea-like Fe3O4/Fe7S8@C core-shell composite as a high-efficiency microwave absorber

“…S3b. The above phenomena suggest that the Fe3O4/Fe7S8@C hierarchical composite conforms to the λ/4 model [13]. The absorption performance of the absorber is determined by the complex…”

“…The Fe3O4@C exhibits the highest dielectric constant, which may be attributed to the following reasons. First, when the Fe3O4 particles are tightly wrapped by the carbon shell, the core-shell interface polarization will be increased due to the difference in dielectric constant and conductivity [13]. In addition, the carbon shell of Fe3O4@C has a higher graphitization degree, which can significantly increase the conductivity of the composite [60].…”

“…To date, great progress has been made in classical magnetic EMW absorber materials (Fe, Co, Ni, and their metal oxides) [10,11]. In particular, iron oxides (such as Fe2O3 and Fe3O4) are high-profile absorber materials by many scholars due to their wide source, low cost, and outstanding magnetic loss [12][13][14]. Their inherently low dielectric properties can be modulated by the coating dielectric composition, which can significantly optimize the basic properties of the material based on the magnetic-dielectric synergy, such as conductivity, high specific surface area, and impedance matching [15].…”

Nickel Iron Layered Double Hydroxide Nanostructures Composited with Carbonyl Iron Powder for Microwave Absorption

“…To visually judge the electromagnetic wave absorption performance of all samples, the reflection loss (RL) value based on transmission line theory can be calculated by the following equation: , .25ex2ex RL 0.25em ( dB ) = 20 log true| Z in − Z 0 Z in + Z 0 true| Z in = Z 0 μ r ε r tanh true( j 2 π italicfd c μ normalr ε normalr true) where ε r and μ r represent the complex permittivity and complex permeability, respectively; f stands for frequency; c stands for the speed of light; and d stands for thickness …”

“…Furthermore, the LDH/CIP composite shows multiple peak vibrations between 8 and 18 GHz, which is due to the exchange resonance caused by the small size effect and surface effect that can produce multiple resonances at this frequency. 36 To visually judge the electromagnetic wave absorption performance of all samples, the reflection loss (RL) value based on transmission line theory can be calculated by the following equation: 37,38…”