Microwave Absorption of Substituted M-type Lead Hexaferrite Nanopowders

M-type lead hexaferrites with compositions of PbFe12O19 and PbSnZnFe10O19 were synthesized by the citrate sol-gel method. The structural and magnetic properties of resultant particles were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and vector network analyzer. The magnetic properties such as saturation magnetization (M-s) and coercivity (H-c) were calculated from the hysteresis loops. Microwave absorption properties of ferrite-polymer composites prepared with different ferrite ratios of 50%, 60%, 70% and 80% have been investigated in the frequency range of 12-20 GHz. The composite powder with 80 wt% lead ferrite possesses good microwave absorption properties. The minimum reflection loss of the composite powder reaches -30 dB at the thickness of 2 mm for composite powder with 80 wt% ferrite. The composite with 80% ferrite content has shown a minimum reflection loss of -24.5 dB at 18.6GHz with the -15 dB bandwidth over the extended frequency range of 16.3-19.4GHz for an absorber thickness of 1.8 mm. The prepared composites can fruitfully be utilized for suppression of electromagnetic interference (EMI) and reduction of radar signatures (stealth technology).