Improvement of the performance of microwave X band absorbers based on pure and doped Ba-hexaferrite

• Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite.
• Formation of a single phase M-hexaferrite, pure or doped when Fe/Ba=10.
• Preparation of microwave absorber of BaCo2Zr(SnTi)0.5Fe8O19/epoxy resin, 50 wt%.
• The absorber exhibits a minimum RL of −29 dB at 12.2 GHz with 2.6 GHz bandwidth.

Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite prepared via mechanical activation. X-ray diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer are used to analyze phases, structures, electromagnetic and microwave absorption properties. The mole ratio of Fe/Ba=10 is detected to be optimum for doping and synthesizing the Ba-hexaferrite. In order to achieve high absorption in X band the ions of Zr4+–Sn4+–Ti4+–M2+ (M=Mg2+, Zn2+, Cu2+, Co2+) are used as dopants. The results indicate the formation of single phase Ba-hexaferrite in either pure or doped compounds without any non-magnetic intermediate phases and with spherical and hexagonal morphologies respectively for the pure and doped ferrite. It is found out that BaCo2Zr(SnTi)0.5Fe8O19 compound has the maximum saturation magnetization (49.80 emu/g). Also the composite of BaCo2Zr(SnTi)0.5Fe8O19 50 wt% in epoxy resin exhibits a minimum reflection loss of −29 dB at 12.2 GHz with 2.6 GHz bandwidth.

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