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 (RLmin) in the nonannealed sample was -46.4 dB at 16 GHz for a 2.8 mm thickness. While, for the annealed sample, RLmin 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.