Preparation of Electromagnetic wave absorber Barium Ferrites for Electromagnetic Environment by liquid State Reaction

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In the present study, we tried the synthesis of Y-type Ba-hexaferrite expected as an electromagnetic wave absorber by the glass ceramic method. The results are summarized as follows.The glasses with composition of 0.1MO[xB_2O_3・yBaO・(1-x-y)Fe_2O_3] were prepared and the precipitation process of Y-type Ba-hexaferrite from the glass matrix was investigated. Y-type Ba-hexaferrite particles were precipitated by heating the glass at temperatures between 820℃ and 1100℃. Based on these results, hexagonal platelets of Y-type Ba-hexaferrite with fairly uniform dimension were obtained as precipitates from the glass matrix by leaching with a dilute HCl solution. The low-temperature formation of Y-type Ba-hexafcrrite was due to a reaction between M-type Ba-ferrite and liquid phase. Substitutional solid solutions of Y-type Ba-hexaferrite (Ba_2Zn_<2-x>Co_xFe_<12>O_<22>) were obtained in all composition range. These Y-type Ba-hexaferrite solid solutions showed electromagnetic absorption spectra at frequency range of 8 to 9 GHz.