Study On The Geometrical Effect Of Microwave-absorbing Properties Of Barium Ferrite

The aim of this paper is to synthesize nano-particles of barium ferrite with hexagonal flake and acicular and to study the effect of the different geometrical samples on microwave-absorbing performance.Coprecipitation-fused-salt method, sol-gel method and local reaction method were used to prepare a series of the barium ferrite crystal particles. Thermal analysis instrument, X-ray diffraction instrument, and a field emission scanning electron microscope were used to investigate differential thermal analysis (DTA) and thermogravimetry (TG) of the precursors, phases constitute, surface morphology, and crystal particle size. The best method and condition of preparing barium ferrite nano-particles with hexagonal flake and with acicular were discussed. And the electromagnetism parameters and reflectivity of the two kinds of barium ferrite samples were tested to examine the effect of the two kinds of samples with different geometrical size on microwave-absorbing performance by vector network analyzer and arch frame method.Experiment results show that when the substitute value of (CoTi) is 1.2,the precursor prepared by coprecipitation-fused-salt method is sintered at 850℃and the barium ferrite nano-particles with hexagonal flake are gained. When the precursor prepared by local reaction method is heat-treated for 10min at 800℃, the barium ferrite nano-particles with acicular are gained. When the coat is 2mm thick, the minimum value of the reflectivity of the barium ferrite nano-particles with hexagonal flake is -9.06dB at the frequency of 12.5GHz, and the band width of less than -8dB attains 8GHz. When the coat is 2mm thick, the minimum value of the reflectivity of the barium ferrite nano-particles with acicular is -13.2dB at the frequency of 14.3GHz, and the band width of less than -8dB attains 9GHz. The band width of less than -10dB of the barium ferrite nano-particles with acicular attains 6.3GHz. So, the barium ferrite nano-particles with acicular are better than the barium ferrite nano-particles with hexagonal flake in microwave-absorption performance.