Preparation and microwave-absorbing property of EP/BaFe_(12)O_(19)/PANI composites

摘要

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/BaFe_(12)O_(19)) was prepared, and then ternary composites of expanded perlite/barium ferrite/polyaniline (EP/BaFe_(12)O_(19)/PANI) were obtained by in-situ oxidative polymerization of aniline on EP/BaFe_(12)O_(19) 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 BaFe_(12)O_(19) particles owing to the existence of the nonmagnetic EP and PANI, the EP/BaFe_(12)O_(19)/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.