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Basic research for the development of portable compact magnetic memory using high coercivity magnetic nanoparticle

使用高矫顽力磁性纳米粒子开发便携式紧凑磁存储器的基础研究

基本信息

批准号：
15360003
负责人：
JEYADEVAN B
金额：
$ 5.82万
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：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15360003/
关键词：
FePt Polyol Process High density magnetic recording Chemical Synthesis Direct Synthesis Crystal Structure Control Size Control Magnetic Alloy Nanoparticle 超磁気記録密度合金磁性ナノ粒子

项目摘要

In this project, the synthesis of magnetic metal and alloy nanoparticles by using the chemical method called "polyol process" was investigated in detail. The reaction parameters such as type of polyol, synthesis temperature, metal ion concentration, reaction promoting agents, and nucleating agents were effectively utilized to control the reaction kinetics to obtain magnetic nanoparticles with required physical properties such as size and crystal structure. This paved the way for the synthesis of magnetic nanoparticles with varying magnetic properties. For example in the cases of transition metal nanoparticles such as cobalt and nickel, the synthesis of particles with diameters ranging from few micron to few tens of nanometer and varying crystal structures was realized. For example, the bulk cobalt is known to have fcc phase at temperatures as high as 421.5℃. However, the cobalt metal particles synthesized using the modified polyol process were found to posses fcc structure at micron si … More ze levels. When the reaction kinetics was enhanced, the particle size was reduced to submicron and even to few tens of nanometer. Along with size reduction, the crystal structure also changed from fcc at micron size range, coexistence of fcc and hcp in the submicron size range and to s and hcp cobalt at nanometer size range. On the other hand, we also succeeded in the synthesis of non-magnetic hcp-Ni nanoparticle of few tens of nanometer in diameter.In the case of the synthesis of magnetic alloy nanoparticles for magnetic recording, we have successfully demonstrated the direct synthesis of L1_0 FePt nanoparticles at low temperature of 553 K using "modified polyol method" without subsequent annealing, whose diameter is 5-10 nm and the intrinsic magnetocrystalline anisotropy field (H_k) is 31 kOe. This indicates that precise control of the reaction kinetics, especially low reduction rate through optimizing the polyol/Pt salt mole ratio and type of polyol are very important for directly synthesizing the L1_0 FePt nanoparticles. CoPt nanoparticles with high magnetocrystalline anisotropy and also particle sizes of 7 nm in diameter were prepared by using the modified polyol process. Furthermore, we also succeeded in selectively fixing FePt and CoPt nanoparticles on a silicon substrate by using APTS as the coupling layer, which prevents the grain growth even at higher annealing temperatures. Though the presence of the highly anisotropic phases was identified the potential of the particles were well below the anticipated values. Although the successful fabrication of recording media using magnetic particles for portable compact memory was not realized, considerable information and knowledge related to both the synthesis of nanoparticles and the fabrication of nanoparticle monolayer film was gathered. Thus, using this information as the base, we will work towards the development of high-density recording medium. Less

本计画以多元醇法合成磁性金属及合金奈米粒子。反应参数如多元醇的类型、合成温度、金属离子浓度、反应促进剂和成核剂被有效地用于控制反应动力学，以获得具有所需物理性质如尺寸和晶体结构的磁性纳米颗粒。这为合成具有不同磁性能的磁性纳米颗粒铺平了道路。例如，在过渡金属纳米颗粒如钴和镍的情况下，实现了直径范围从几微米到几十纳米并且具有不同晶体结构的颗粒的合成。例如，已知本体钴在高达421.5℃的温度下具有fcc相。而采用改进的多元醇法合成的钴金属颗粒在微米级时具有fcc结构 ...更多信息 ze水平。当反应动力学增强时，颗粒尺寸减小到亚微米甚至几十纳米。沿着尺寸的减小，钴的晶体结构也由微米级的fcc，亚微米级的fcc和hcp共存，到纳米级的s和hcp共存。另一方面，我们还成功地合成了直径为几十纳米的非磁性hcp-Ni纳米颗粒。在磁记录用磁性合金纳米颗粒的合成中，我们成功地证明了在553 K的低温下使用“改性多元醇法”直接合成L1_0 FePt纳米颗粒，而无需后续退火，其直径为5-10 nm，内禀磁晶各向异性场（H_k）为31 kOe。这表明通过优化多元醇/Pt盐的摩尔比和多元醇的种类来精确控制反应动力学，特别是降低还原速率，对于直接合成L1_0 FePt纳米颗粒是非常重要的。采用改进的多元醇法制备了具有高磁晶各向异性的CoPt纳米颗粒，粒径为7 nm。此外，我们还成功地选择性地固定FePt和CoPt纳米粒子在硅衬底上，通过使用APTS作为耦合层，即使在较高的退火温度下也可以防止晶粒生长。虽然高度各向异性相的存在被确定的颗粒的电位远低于预期值。虽然没有实现使用磁性颗粒的记录介质的成功制造用于便携式紧凑存储器，但是收集了与纳米颗粒的合成和纳米颗粒单层膜的制造两者相关的大量信息和知识。因此，以这些信息为基础，我们将致力于开发高密度记录介质。少