自组装核壳耦合型纳米复合磁性材料的微结构建立与磁性控制机制

In this project, Sm-Co@Fe-Co exchange-coupled magnetic nano-powders which have core-shell microstructrue will be prepared using the seed-assisted hydrothermal method, with the help of Sm-Co nanoparticles as seeds introduced into the reducing solution of Fe-Co salt. Then bulk magnets of Sm-Co/Fe-Co are to be made from the obtained nano-powders by spark plasma sintering (SPS) technique. The present work is about to create a new hard/soft nano-phases exchange coupled system with a core-shell microstructure and study on the formation and controlling mechanism of the core-shell microstructure, which will contribute to controlling the size and distribution of magnetic phases, increasing the contact area between the two phases and improving the coupling strength in the exchange-coupled system. To enhance the lattice match level and get a strong coupling effect, more emphasis should be put on the microstructure and composition controllability of the core-shell boundary. Furthermore, this study will concerns about the restraining function of the core-shell boundaries and the solubility limit of Fe and Co in SmCox on the growing up quickly of the grains, which may offer a solution to the puzzles that the grains prefer to grow up and the magnetic phases are hard to distribute uniformly when the nanoparticles are heated in a mould under a high pressure. All in all, this project aims at expanding a new pathway for the fabrication of exchange coupled nano-magnets and illuminating the controlling mechanism of exchange coupling, realizing the designability of such materials and approaching the theoretical magnetic properties. Consequently, the research achievements can provide important theoretical basis and empirical experience for the development of exchange coupled magnetic materials with high performance.

本项目将Sm-Co纳米颗粒引入Fe-Co盐液相还原体系作为晶种，通过晶种辅助的水热法制备Sm-Co@Fe-Co核@壳结构交换耦合型纳米磁粉，并用等离子快速烧结技术制备Sm-Co/Fe-Co块状磁体。项目将建立具有核@壳结构的硬/软纳米磁性相交换耦合新体系，研究核@壳结构的形成及控制机理，解决目前耦合体系中存在的磁性相尺度与分布不可控，两相接触面积偏小，交换耦合强度不高等问题；利用核@壳界面微结构成分的可调性，提高相界面晶格匹配度，增强交换耦合效果；利用核@壳相界面与Fe、Co在SmCox中的溶解极限对晶粒快速生长的阻止效应，解决纳米颗粒块体化加热过程中晶粒易长大、磁性相体积分布不均的问题。项目旨在开拓纳米耦合磁体制备的新思路并阐明其控制机制，进一步实现此类材料的可设计性并接近理论磁性能，为开辟生产高磁性能耦合型磁性材料的新途径提供重要的理论基础和实验参考。

本项目将Sm-Co纳米颗粒引入Fe-Co盐液相还原体系作为晶种，通过晶种辅助的化学法制备了Sm-Co@Fe-Co核@壳结构交换耦合型纳米磁粉与Sm-Co/Fe-Co块状磁体。项目建立了具有核@壳结构的硬/软纳米磁性相交换耦合新体系，研究了核@壳结构的形成及控制机理，讨论了磁性相尺度与分布不可控，两相接触面积偏小，交换耦合强度不高等问题；利用核@壳界面微结构成分的可调性，提高了相界面晶格匹配度，增强交换耦合效果；探究了核@壳相界面与Fe、Co在SmCox中的溶解极限对晶粒快速生长的阻止效应等问题。项目为开辟生产高磁性能耦合型磁性材料的新途径提供了重要的理论基础和实验参考。