Superior microwave absorption ability of CuFe2O4/MWCNT at whole Ku-band and half X-band

Abstract

Recently, with the increasing progress of telecommunication systems and the development of high-range antennas, especially microwave antennas, the pollution caused by them has become very worrying. So, many efforts are being made to design absorbents which protect the environment from electromagnetic waves. Many reports have proved the extraordinary effect of absorbents containing carbon and ferrites. Here, the microwave absorption capabilities of two samples of CuFe₂O₄/MWCNT composites (annealed at 400 °C and unannealed) were studied in which CuFe₂O₄ nanoparticles (NPs) were decorated on multiwalled carbon nanotubes (MWCNTs) via a two-step method. First, CuFe₂O₄ NPs were synthesized at an optimum condition to have narrow size distribution (<10 nm) and high saturation magnetization of 47 emu g⁻¹. Then, the CuFe₂O₄ NPs were used to decorate MWCNTs affording CuFe₂O₄/MWCNT. Half of CuFe₂O₄/MWCNT was annealed at 400 °C for 3 h and the rest of CuFe₂O₄/MWCNT remained nonannealed. The minimum reflection loss (RL_min) in the nonannealed sample was −46.4 dB at 16 GHz for a 2.8 mm thickness. While, for the annealed sample, RL_min reached −69 dB at 10 GHz for a 3.4 mm thickness. In the nonannealed sample, the effective absorption bandwidth was 3.8 GHz, but this value was significantly increased to 8.5 GHz for the annealed sample at 3.2 and 3.4 mm thickness, which covered whole X and Ku bands.