Lightweight broadband microwave absorbers of core-shell (polypyrrole/NiZn ferrite) nanocomposites in the X-band: insights on interfacial polarization

Polypyrrole/Ni0.5Zn0.5Fe2O4 (PPy/NiZn ferrite) nanocomposites are prepared using the in-situ chemical oxidative polymerization method of pyrrole in the presence of the ferrite. The composites are characterized using scanning and transmission electron microscopies, vibrating sample magnetometry, thermal gravimetric analysis, X-ray diffractometry, Fourier transform infrared spectroscopy and UV-visible spectroscopy. The microwave absorption characteristics are performed by measuring the reflection loss in the X-band. The results indicate the presence of a maximum reflection loss of -30.0 dB at 10.9GHz with a matching thickness of 3.0mm and a bandwidth of 3.6GHz for a weight ratio PPy/NiZn ferrite of 2:1 and a loading not exceeding 7.5% w/w of nanocomposite in a host matrix of paraffin wax. The surface density of the absorber is only 2.74kg/m(2). The role of interfacial polarization in promoting microwave absorption characteristics is also highlighted.