Preparation and microwave-absorbing property of EP/BaFe 12 O 19 /PANI composites

In this paper, we introduced expanded perlite (EP) into the system of ferrite composites for the first time. By sol-gel self-propagating combustion method, expanded perlite/barium ferrite (EP/BaFe12O19) was prepared, and then ternary composites of expanded perlite/barium ferrite/polyaniline (EP/BaFe12O19/PANI) were obtained by in-situ oxidative polymerization of aniline on EP/BaFe12O19 mixture. Although, as is well known, the values of saturation magnetization (Ms), remnant magnetization (Mr) and coercivity (Hc) of composites are all lower than the pure BaFe12O19 particles owing to the existence of the nonmagnetic EP and PANI, the EP/BaFe12O19/PANI composites exhibit absorption characteristics at the range of 2–18 GHz, the effective absorption bandwidth (less than −4 dB) reached 12.12 GHz and the minimum reflection loss of −5.66 dB at 8.48 GHz with only 2 mm thickness of absorbing layer. So the composites could resist urban electromagnetic pollution, such as wireless network, communication and so on, effectively.