The role of multi-walled carbon nanotubes on the magnetic and reflection loss characteristics of substituted strontium ferrite nanoparticles

Abstract

Substituted strontium ferrite SrFe12−x(Ni0.5Mn0.5Zr)x/2O19/multi-walled carbon nanotubes (MWCNTs) composites were prepared by a sol–gel method. X-ray diffraction patterns confirm the formation of single phase ferrite nanoparticle and nanocomposites of ferrite/carbon nanotubes. Fourier transform infrared spectroscopy demonstrates the existence of functional groups on the surface of carbon nanotubes. Superconducting quantum interference device measurements showed that the values of specific saturation magnetization increases, while coercivity decreases with an increase in substitution content. Zero field cooled magnetization and field cooled magnetization curves display that with an increase in substitution content, the blocking temperature increases. Field emission scanning electron microscopy micrographs demonstrate that ferrite nanoparticles were attached on external surfaces of the carbon nanotubes. The investigation of the microwave absorption indicates that with an addition of carbon nanotubes, the real and imaginary parts of permittivity and reflection loss enhanced. It is found that with increasing the thickness of absorbers, the resonance frequencies shift to lower regime.