兰州大学机构库 >物理科学与技术学院
易面各向异性稀土金属间化合物磁粉的微波磁性研究
Alternative TitleMicrowave magnetic properties of rare earth intermetallic powder with easy-plane anisotropy
池啸
Thesis Advisor王涛
2013-05-25
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
KeywordY2Fe17 Y2Fe17Nx Y2Fe17-xCox 熔体快淬 穆斯堡尔谱 平面各向异性 锥面各向异性 微波吸收 反射损耗
Abstract在国防及民用工业中,磁性材料的微波磁性质变的越来越重要,这是因为目前磁性电子器件在高频下的使用强烈地依赖于磁性材料在高频下的磁行为,例如移动电话,wifi的接入都需要材料有好的高频吸波性能。传统的微波磁性材料遵从Snoek极限理论,即磁性材料在高频下的性质只依赖于材料的饱和磁化强度,这样使得材料在高频下的使用及研究受到了极大地限制。为了突破Snoek极限条件的限制,就必须提出新的微波磁性理论模型及材料制备手段。 上个世纪五十年代荷兰飞利浦实验室发现具有平面各向异性铁氧体材料。这种具有平面各向异性的材料在高频下有更高的磁导率及自然共振频率。研究表明这种具有平面各向异性材料的微波磁性质不仅与其饱和磁化强度有关,还与这种材料的面内和面外各向异性场有关,这就使得我们可以在制备样品的时候人为地调控材料的形状或掺杂,改变材料的面内和面外各向异性场,从而提高材料的微波磁性质。 由上面的理论指导,本论文制备了具有易面各向异性的Y2Fe17、Y2Fe17Nx及Y2Fe17-xCox稀土-3d过渡金属化合物磁粉,研究了此系列样品的磁晶各向异性,并且讨论了平面各向异性材料的微波磁性质及微波吸收性质。
Other AbstractHigh frequency permeability of magnetic materials is becoming more and more important in nowadays national defense industry. It's because the performance of magnetic devices operating at high frequency strongly depends on the permeability dispersion behaviors, such as cellular phones, common-mode choke coils and corresponding electromagnetic (EM) wave absorbers. Especially, the EM wave absorption properties in S-band (2-4 GHz). For example, Wi-Fi network at 2.4 GHz, microwave ovens at 2.45 GHz, and fixed satellite at 2.4, 2.6 GHz. According to current EM wave theories, the permeability (μr) of materials should be improved to obtain a smaller matching thickness (tm) in a lower S-band frequency. Generally, the capability of traditional high frequency magnetic materials with uniaxial anisotropy can be well discribed by Snoek's theory, the product of the initial permeability and resonance frequency is proportional to the saturation magnetization, which therefore significantly limits the application of materials. However, in recent years, the planar ferrites, especially planar anisotropy soft magnetic thin films and planar anisotropy flake-shaped particles, have shown higher resonance frequency and higher permeability at higher frequencies than that of the bulk materials and most spherical particle composites. The high frequency magnetic properties then can be improved by changing out-of-plane and in-plane magnetocrystalline anisotropies. According to the theory above, the Y2Fe17, Y2Fe17Nx and Y2Fe17-xCox particles have been prepared and the magnetocrystalline anisotropy properties were also studied using different methods. At last, we discussed the high frequency magnetic properties of Y2Fe17, Y2Fe17Nx and Y2Fe17-xCox paraffin compounds. The main results are obtained as follows: Y2Fe17 magnetic powders The intensity of the [004] diffraction is strongly enhanced when XRD measurement is performed on the oriented composite surface perpendicular to the cylindrical axis proved that the Y2Fe17 are planar anisotropy magnetic structures in atmosphere temperature; The Snoek value is 4.6 GHz for the Y2Fe17 composite with 30 vol %, where the Ms is the saturation magnetization of Y2Fe17 powders. However, for planar anisotropy Y2Fe17 powders, the value of the permeability is related to the out of plane anisotropy-field Ha and in plane anisotropy-field Hp, it is observably found that the product of the initial permeability and the nature resonance is larger than the ...
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/229087
Collection物理科学与技术学院
Recommended Citation
GB/T 7714
池啸. 易面各向异性稀土金属间化合物磁粉的微波磁性研究[D]. 兰州. 兰州大学,2013.
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