Synthesis of multi-walled carbon nanotube/doped barium hexaferrite nanocomposites: An investigation of structural, magnetic and microwave absorption properties

Nanocomposite BaCuxMgxZr2xFe12−4xO19/MWCNTs with different substitutions (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) was synthesized using a two stage chemical route. The reported structural, magnetic and microwave absorption properties of samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM) and vector network analysis (VNA). Results showed that the doped hexaferrite nanoparticles and BaCuxMgxZr2xFe12−4xO19/MWCNTs nanocomposites were synthesized successfully in all samples. The SEM and TEM micrographs proved that the MWCNTs structure was not destroyed after the acid treatment process while the nanoparticles could be absorbed on the surface of MWCNTs as a layer. The evaluation of VSM analysis also proved the maximum magnetization increase at first, and then decreased on the further increase of the dopant content. The values of coercivity varied in the range of 4689-251 (G). The values of real and imaginary parts of the permittivity of the BaM samples (x=0.0-0.5) with MWCNT was much higher than those of the BaM samples without MWCNT. It was also found that the highly doped sample (x=0.5)/MWCNT had a minimum reflection loss value of -23.1 dB with a suitable bandwidth about 6 GHz at a matching thickness of 2.1 mm. In addition, the reflection loss proved to be dependent on the absorber thickness; while with increasing the thickness of absorbers, the resonance frequencies shifted to a lower regime.