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 (Ms) and coercivity (Hc) 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).