钴铁合金基磁相互作用纳米体系的设计、制备及磁性质研究

项目名称： 钴铁合金基磁相互作用纳米体系的设计、制备及磁性质研究

项目编号： No.51471001

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 一般工业技术

项目作者： 马永青

作者单位： 安徽大学

项目金额： 85万元

中文摘要： Co-Fe合金在所有已知合金磁体中饱和磁化强度最大，且是典型的软磁材料，矫顽力很小。将其与矫顽力较大的硬磁材料CoFe2O4复合，调控磁性能，可以拓宽其应用领域。在已报道的Co-Fe/CoFe2O4纳米复合体系的结果中，剩磁比很小，且对机理的解释也莫衷一是，关键问题在于：1）以往采用液相制备→固相还原途径所制备的粒子聚集严重，致使样品中粒子间偶极相互作用抑制了晶粒间交换耦合作用，导致小的剩磁比。2）以往未系统研究Co-Fe/CoFe2O4中的偶极相互作用，尽管偶极作用普遍存在于纳米体系中且对磁性有显著影响。本项目精心设计制备环节，拟采用液相制备→液相还原（氧化）→液相隔离等技术合成样品，系统研究单相Co-Fe合金、Co-Fe/CoFe2O4复合体系中偶极相互作用对磁性质的影响：获得磁状态（超铁磁、超顺磁、超自旋玻璃）与粒子间距、磁矩之间关系的相图；揭示矫顽力、剩磁比与偶极作用间的内在关联。

中文关键词： 钴铁合金；磁性纳米复合材料；偶极相互作用；交换耦合相互作用；磁性能

英文摘要： Co-Fe alloy has the largest saturation magnetization among all known alloy magnets, and is a kind of typical soft magnetic material with a small coercivity. Its application fields can be expanded if its magnetic performance is improved by compounding with CoFe2O4 with the higher coercivity. In the previously reported results of Co-Fe/CoFe2O4 nanocomposites, the remanence to saturation magnetization ratio is very small and the interpretation to the underlying mechanism is still a matter of academic discussion. Key issues in previous reports are as follows: 1) Particles, obtained through the routes of preparation in liquid phase followed by reduction in solid phase, conglomerate seriously, causing that the interparticle dipolar interaction suppresses the exchange coupling interaction and consequently leading to the small remanence to saturation magnetization ratio. 2) The dipolar interaction in Co-Fe alloys or in Co-Fe/CoFe2O4 nanocomposites has not been systematically studied so far, even though the dipolar interaction widely consists in nano-scaled system and significantly affects magnetic properties. This project carefully designs the fabrication stage, utilizing techniques of preparing, reducing (oxidizing) and separating in liquid phase, and systematically investigates the effects of interparticle dipolar interaction on the magnetic properties in single-phase Co-Fe alloys or in Co-Fe/CoFe2O4 nanocomposites, for the purposes of (1) obtaining the phase diagram of magnetic states (superferromagnetism, superparamagnetism and superspin glass, etc.) versus distances and moments of particles and (2) revealing inherent correlation between the coercivity, remanence to saturation magnetization ratio and the dipolar interaction.

英文关键词： Co-Fe alloys;Magnetic nanocomposites;Dipolar interaction;Exchang-coupling interaction;Magnetic performance