Microwave Absorption in the GHz Range of Nanostructure Produced by Disproportionation Reaction of Rare Earth-Iron Compound

稀土铁化合物歧化反应产生的纳米结构在 GHz 范围内的微波吸收

• 批准号: 12450276
• 负责人: SUGIMOTO Satoshi
• 金额: $ 4.67万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450276/
• 关键词: rare earth compound; microwaye absorber; disproportionation; reflection loss; permeability; matching thickness; nano size; matching frequency; インピーダンス; 希土類化合物; 窒化; 水素化

For the 1-5 GHz frequency range, both Spinel-type ferrites and metallic magnetic materials can be used as electromagnetic wave absorbers. However, because the latter materials have larger values of saturation magnetization, their Snoek's limit are at a higher frequency and so their values of relative complex permeability remain high in this frequency range. Therefore, it is possible to make thinner absorbers from metallic magnetic materials.The magnetization of electrically conductive magnetic materials, induced by electromagnetic waves, decreases due to eddy current losses. For this reason, it is best to use smaller particles, compared to the skindepth, when making electromagnetic wave absorbers from such materials. In this study, the possibility of using the disproportionation reaction of the Sm_2Fe_<17> compound for the production of powders with a fine α-Fe structure was investigated, for use as electromagnetic wave absorbers that can operate in the GHz frequency range. A fine α-Fe … More / SmH_2 or α-Fe / SmO structure with a sub-micrometer size is formed from the Sm_2Fe_<17> compound after disproportionation in hydrogen or air, respectively. In this way, magnetic powders with a fine structure of α-Fe were obtained. The powders disproportionated in hydrogen, were heated in air in order to oxidize the Sm hydride, to give a α-Fe / SmO two-phase microstructure, and thereby increase the resistivity of the powders. Toroidally shaped epoxy-resin composites were made from this powder, and the microwave absorption properties of these samples were measured. An undisproportionated sample did not show any electromagnetic wave absorption in this frequency range. However, the disproportionated samples (heated in hydrogen at 873 K for 1 hour, milled for 30 minutes and oxidized at 473 K for 2 hours in air) exhibited electromagnetic wave absorption (R.L.< -20dB) in the frequency (f_m) range 0.73 to 1.30 GHz, for absorber thicknesses (dm) ranging from 13.1 to 7.9 mm, respectively. The disproportionated samples in air (heated at 473K for 2 hours and milled for 30 minutes) also showed good electromagnetic wave absorption properties (f_m=-1.21 - 2.50 GHz and d_m= 8.0 - 4.2 GHz). It is concluded that the disproportionation reaction, in either hydrogen or in air, is a useful method for the production of powders with a fine α-Fe structure, which can be used for microwave absorbers that operate in the several GHz range. Less

对于1-5 GHz的频率范围，尖晶石型铁氧体和磁性材料都可以用作电磁波吸收器，使用后一种材料具有较大的饱和磁化值XEABIS在该频率范围内保持高，由电磁波诱导的磁化。因此，与Skindepth相比，最好使用较小的颗粒使用SM_2FE_ <17>组合使用粉状α-Fe结构的粉末的反应，用作可以打开的SMO结构的电磁波吸收器。 <17>在氢或空气中不屈服的化合物，以这种方式，在氢气中获得了具有α-FE的良好结构的磁粉。 Fe / SMO两相微观结构。空气中的电磁波吸收（R.L. <-20dB）的频率（F_M）范围为0.73至1.30 GHz，吸收厚度（DM）范围为13.1至7.9 mm。显示出良好的电磁波吸收（F_M = -1.21-2.50 GHz，D_M = 8.0-4.2 GHz）。较少的。