Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka, Fukuoka-shi, Fukuoka 819-0395, Japan.
J Colloid Interface Sci. 2010 May 15;345(2):143-8. doi: 10.1016/j.jcis.2010.01.077. Epub 2010 Feb 1.
We first succeeded in synthesizing ferrite nanoparticles containing Nd and B elements by a chemical route using a polyol process. The lattice constants of the ferrite nanoparticles were equivalent to 8.39Å of the lattice constant for Fe(3)O(4) with the spinel structure in a bulk state independently of the size in diameter and composition (Fe:Nd:B). The size in diameter was actually dominated by the amount of ligands (oleic acid and oleylamine) coating the nanoparticles and easily tuned by changing refluxing-time under reaction. The spinel-structured ferrite nanoparticles containing Nd and B elements showed large coercivity as compared to Fe(3)O(4) nanoparticles with the spinel structure, which were prepared by the same chemical method. By doping Nd and B elements into the spinel structure of ferrite, magnetic anisotropy increased in comparison with Fe(3)O(4) nanoparticles. According to the analysis of magnetization curve using the modified Langevin function, the ferrite nanoparticles displayed the coexistence of superparamagnetic and antiferromagnetic phases. The ferrite nanoparticles containing Nd and B elements exhibited magnetic core/shell structure on the basis of various magnetic properties. The interface effect between the superparamagnetic core and antiferromagnetic shell might enhance the effective magnetic anisotropy of the ferrite nanoparticles containing Nd and B elements.
我们首次通过使用多元醇法的化学途径成功合成了含 Nd 和 B 元素的铁氧体纳米粒子。这些铁氧体纳米粒子的晶格常数与块状体中具有尖晶石结构的 Fe(3)O(4)的晶格常数 8.39Å 相当，而与直径和组成（Fe:Nd:B）无关。直径的大小实际上由覆盖纳米粒子的配体（油酸和油胺）的量决定，通过改变反应过程中的回流时间很容易进行调整。与通过相同化学方法制备的具有尖晶石结构的 Fe(3)O(4)纳米粒子相比，含 Nd 和 B 元素的尖晶石结构铁氧体纳米粒子具有较大的矫顽力。通过在铁氧体的尖晶石结构中掺杂 Nd 和 B 元素，与 Fe(3)O(4)纳米粒子相比，磁各向异性增加。根据使用修正朗之万函数对磁化曲线的分析，铁氧体纳米粒子显示出超顺磁和反铁磁相的共存。基于各种磁性能，含 Nd 和 B 元素的铁氧体纳米粒子表现出磁性核/壳结构。超顺磁核与反铁磁壳之间的界面效应可能会增强含 Nd 和 B 元素的铁氧体纳米粒子的有效磁各向异性。
