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，尖晶石型铁氧体和金属磁性材料都可以用作电磁波吸收器。但是，由于后一种材料具有较高的饱和磁化值，因此它们的SNOEK极限较高频率，因此它们的相对复杂渗透率值在此频率范围内仍然很高。因此，可以从金属磁性材料中制成更薄的吸收剂。通过电子波诱导的导电磁性材料的磁化，由于涡流损耗而减少。因此，与Skindepth相比，在从这些材料中吸收电子波时，最好使用较小的颗粒。在这项研究中，研究了使用SM_2FE_ <17>化合物的不成比例反应来生产具有精细α-FE结构的粉末的可能性，用作可以在GHz频率范围内运行的电子波吸收器。精细的α-FE…分别是由SM_2FE_ <17>分别在氢或空气中占相反的SM_2FE_ <17>化合物形成的，具有亚微米尺寸的更多 / SMH_2或α-FE / SMO结构。以这种方式，获得了具有α-FE的精细结构的磁粉。在氢气中不成比例的粉末在空气中加热，以使Sm Hydrode氧化，从而产生α-FE / SMO两相微结构，从而增加了粉末的电阻。用这种粉末制成环状环氧酸膜组成，并测量这些样品的微波损耗特性。在此频率范围内，不合适的样品未显示任何电磁波损失。然而，不成比例的样品（在873 K中加热1小时，在473 k下铣削30分钟，在空气中氧化2小时）暴露的电磁波抽象（R.L. <-20dB）在频率（F_M）的0.73至1.30 GHz中，范围为0.73至1.30 GHz，可吸收厚度为13.9.9.9.9.19.11 n.9 n.1。空气中的不成比例样品（在473K加热2小时并铣削30分钟）也显示出良好的电磁波抽象性能（F_M = -1.21-2.50 GHz，D_M = 8.0-4.2 GHz）。得出的结论是，在氢或空气中，占比例的反应是一种有用的方法，用于生产具有精细α-FE结构的粉末，可用于在几个GHz范围内运行的微波吸收器。较少的