Characterization microwave absorption from active carbon/BaSmxFe12-xO19/polypyrrole composites analyzed with a more rigorous method

There are problems with the conventional method of determining reflection loss for microwave absorption material. In particular, it is concluded that the ability of a material to absorb microwaves is related with sample thickness of the material. Based on this wrong conclusion, a model is thenproposed on the quarter-wavelength's sample thickness. However, it is shown in the present work that the conclusion together with the model is incorrect and that the associated experimental work needs therefore to be re-evaluated. In this work we evaluate our own experimental work on microwave absorption of a composite correctly and demonstrate the errors in the previous method. C/BaSmxFe12-xO19 has been prepared by the hydrothermal method and C/BaSmxFe12-xO19/PPY by in situ polymerization. The microwave absorption of the composites has then been characterized with an appropriate method. The maximum reflection loss was achieved at x=0.2 consistently for both C/BaSmxFe12-xO19 and C/BaSmxFe12-xO19/PPY. The result shows that the components of active carbon, polypyrrole, and ferrite in the composites have a positive cooperating effect on microwave absorption. It is also clearly demonstrated that the result is independent of sample thickness.