Laminated magnetic graphene with enhanced electromagnetic wave absorption properties

Abstract

Graphene is highly desirable as an electromagnetic wave absorber because of its high dielectric loss and low density. Nevertheless, pure graphene is found to be non-magnetic and contributes to microwave energy absorption mostly because of its dielectric loss, and the electromagnetic parameters of pure graphene, which are out of balance, result in a bad impedance matching characteristic. In this paper, we report a facile solvothermal route to synthesize laminated magnetic graphene. The results show that there have been significant changes in the electromagnetic properties of magnetic graphene when compared with pure graphene. Especially the dielectric Cole-Cole semicircle suggests that there are Debye relaxation processes in the laminated magnetic graphene, which prove beneficial to enhance the dielectric loss. We also proposed an electromagnetic complementary theory to explain how laminated magnetic graphene, with the combined advantages of graphene and magnetic particles, helps to improve the standard of impedance matching for electromagnetic wave absorbing materials. Besides, microwave absorption properties indicate that the reflection loss of the as-prepared composite is below À10 dB (90% absorption) at 10.4-13.2 GHz with a coating layer thickness of 2.0 mm. This further confirms that the nanoscale surface modification of magnetic particles on graphene makes graphenebased composites have a certain research value in electromagnetic wave absorption.

MnO2 decorated graphene nanoribbons with superior permittivity and excellent microwave shielding properties

“…Conventional microwave shielding materials (metals and magnetic materials) have limited practical applications due to their high specic gravity, difficulty in formulation and lack of proper response to gigahertz frequencies. 40 The frequency dependence of microwave absorption is a key criterion in selecting materials for EMI shielding applications. MnO 2 and graphene were selected in our experiments because of their high dielectric and absorption properties, respectively.…”

Barium ferrite decorated reduced graphene oxide nanocomposite for effective electromagnetic interference shielding

“…Desired amounts of Ba(NO 3 ) 2 and Fe(NO 3 ) 3 were dissolved in a minimum amount of distilled water to get a clear solution. The molar ratio of Ba to Fe was kept 1 : 11.5.…”

“…The molar ratio of Ba to Fe was kept 1 : 11.5. An aqueous solution of citric acid was mixed with the nitrate solution (mixture of Ba(NO 3 ) 2 and Fe(NO 3 ) 3 ). The molar ratio of citric acid to total moles of nitrate ions was fixed at 1 : 1.…”

“…5,10,19 Graphene is highly desirable as an electromagnetic wave absorber at high frequencies over the gigahertz range due to its high dielectric loss and low density. 2 Barium ferrites (BaFe 12 O 19 ) are well-known hard magnetic materials, which find applications in many fields such as permanent magnets, magnetic recording media, microwave devices and electromagnetic interference shielding. 20 Barium ferrite possesses large saturation magnetization, high Curie temperature together with excellent chemical stability and corrosion resistivity.…”

Strengthened electromagnetic absorption performance derived from synergistic effect of carbon nanotube hybrid with Co@C beads

“…As presented in Fig. 5 [44], and Co 20 Ni 80 alloy (< 100 Oe) [45], in favor of achieving thin absorption thickness at high frequency. Eddy current loss is another factor that can influence the magnetic loss and can be calculated by Eq.…”