New insights on microwave absorption characteristics of magnetodielectric powders: Effect of matrix chemical nature and loading percentage

This work presents the preparation of novel microwave absorbing materials (MAMs) based on a combination of two hard ferrites decorated with MWCNTs, namely (SrFe10CoTiO19@MWCNTs and BaFe10CoTiO19@MWCNTs) with or without coating with polypyrrole (PPY). The hard ferrites cores are prepared using the combustion method, while the shell of PPY is deposited by oxidative polymerization method on the ferrite core. X-ray diffractometry (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and vector network analysis (VNA) are performed for microstructural, magnetic and electromagnetic characterization of the MAMs. Also, this work investigates the influence of the chemical nature of hosting matrix and loading percentage on the microwave absorbing characteristics of the MAMs. Results indicate that MAMs exhibit quite different microwave absorbing characteristics depending on the chemical nature of the hosting matrix (polyester vs paraffin). The presence of polar groups in polyester resin has beneficial effects on the microwave absorbing characteristics by enhancing the minimum reflection loss (RL). The frequency of the minimum RL is also blueshifted by 0.5 GHz when passing from paraffin to polyester hosting matrix. Also, coating the ferritic core with an appropriate amount of polypyrrole as a dielectric shell reduces the loading percentage necessary to obtain promising RL characteristics.