The Effect of Carbon Nanotubes in Improving the Electromagnetic Behavior of W-type Hexaferrite Nanoparticles Doped With Mn and Ca Cations

Dealing with the destructive effects of electromagnetic waves requires materials with the ability to lose magnetic and electrical energies. These materials are mainly composed of a magnetic material and an electrically conductive material. In the present research, at first, strontium ferrite nanoparticles doped with manganese and calcium with the formula of SrCo2-X(Mn Ca)X/2Fe16O27 (x=0.0-0.5) were synthesized by co-precipitation method. Then these nanoparticles were composited together with functionalized carbon nanotubes (with a volume ratio of 1 to 5%). X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, vibrating sample magnetometer, and vector network analyzer were used to investigate the structural, magnetic, and microwave properties of the samples. The X-ray diffraction pattern results showed that the strontium ferrite phase was formed in all compounds, and there was no evidence of any impurities in the samples. FE-SEM results indicated that the particles completely covered the outer walls of the carbon nanotubes. Magnetometer test results also showed that with an increase in the amount of manganese and calcium cations in strontium ferrite, the saturation magnetization decreased and the coercive force increased. Reflection losses were also at least 30% higher in composite samples than those of in ferrite samples. The highest reflection loss (7.42 dB at a frequency of 1.12 GHz) was observed in the nanocomposite sample containing 5% by volume of carbon nanotubes. However, based on the results, the sample containing 4% by volume of carbon nanotubes had a wider absorption bandwidth compared to other samples.