In situ synthesis of core–shell nanocomposites based on polyaniline/Ni–Zn ferrite and enhanced microwave absorbing properties

Core–shell nanocomposites based on polyaniline/Ni–Zn ferrite (PANI-NZFO) were successfully fabricated by a method of in situ oxidative polymerization, and the aggregation of Ni–Zn ferrite (NZFO) nanospheres can be controlled through adjusting the weight ratio of NZFO/aniline (NZFO/ANI). As a result, the sample with NZFO/ANI weight ratio of 3:100 exhibits the optimal reflection loss (RL) value of − 46.5 dB. Particularly, PANI-NZFO present excellent dielectric loss (0.18 < tanδe < 0.35) due to the coating of PANI. TEM images show the core–shell structure of PANI-NZFO and the dispersibility of NZFO is favorable. In order to avoid the NZFO nanospheres from being damaged by the acid, their surface was firstly grafted with amidogen (–NH2). Simultaneously, it is clear that the NZFO nanospheres haven’t been destroyed during the process of coating, which has been confirmed by XRD patterns, and a formation mechanism was designed. FTIR spectra indicate that the coating observed in TEM images is exactly polyaniline (PANI). The effects of NZFO/ANI weight ratio (or conductivity), volume fraction (of PANI-NZFO/paraffin containing PANI-NZFO) and layer thickness on microwave absorbing properties were investigated at room temperature in the frequency range of 0–18 GHz.