The dielectric, magnetic and microwave absorption properties of Cu-substituted Mg-Ni spinel ferrite-MWCNT nanocomposites

The nanocomposites of Cu-substituted Mg-Ni spinel ferrite and multi-walled carbon nanotubes (MWCNT) are synthesized, and the structural, magnetic, dielectric and microwave absorption properties are investigated. The formation of an almost single-phase cubic spinel structure is confirmed by the XRD patterns. The presence of the functional groups on the MWCNT surfaces and the formation of the nanocomposites are approved by the FTIR spectroscopy. MWCNTs are well coated with the ferrite nanoparticles according to the FESEM images. The results of VSM analysis show that all of the samples are soft magnetic materials with potential applications in magnetic field sensing and information storage technologies. The effects of substituting Cu atoms and adding MWCNTs on the dielectric and microwave absorption properties of the samples are also investigated using the vector network analyzer. The addition of MWCNTs considerably increases the permittivity, impedance matching and microwave absorption of the materials. The origin of the changes is considered, and the nanocomposites with high concentration of Cu (+2) are suggested as the high efficiency lightweight absorbers.