Effect of carbon reinforcement on the EMI shielding response of LiFe5O8 ceramics

Abstract

Carbon black (CB) reinforced lithium ferrite composites (LFO/CB) are synthesized to enhance EMI (electromagnetic interference) shielding effectiveness (SE) as nowadays EMI pollution is becoming a serious matter of concern for technology as well as human health. The formation of pure phase lithium ferrite and composites are analyzed. Though saturation magnetization decreased with the incorporation of CB, it did not create any huge decrement. Shielding efficiency is analyzed in the X band (8.2–12.4 GHz) and Ku (12.4–18 GHz) band frequency range. The highest total SE (28 dB) is obtained for 20 wt% of CB with LFO (3 mm thickness), out of which reflection-based shielding effectiveness (SER) is 4.58 dB and absorption based (SEA) is 23.17 dB. The highest absorption efficiency of the composites is measured to be ~99.68% for both LFO/CB (15) and LFO/CB (20) in the broad frequency range (8.2–18 GHz), which confirmed that the composite provides absorption-based SE rather than reflection based. Both real and imaginary part of permittivity drastically increased with incorporation of CB concentration (LFO: ε’ = 4, ε“= 0.11; LFO/CB (20) : ε’ = 46, ε”= 19.05 @8.2 GHz). Complex permeability also increased with CB content. However, dielectric, magnetic, and EMI shielding responses can be tailored by governing the amount of ferrite as well as carbon compound. Further, this study confirms that LFO/CB composites can be a potential candidate for application in the defense and telecommunication sector.