Abstract：
Binary superparticles formed by self-assembling two different types of nanoparticles may utilize the synergistic interactions and create advanced multifunctional materials. Bi-magnetic superparticles with a core-shell structure have unique properties due to their specific spatial configurations. Herein, we built Mn3O4@Ni core-shell binary superparticles via an emulsion self-assembly technique. The superparticles are generated with a spherical morphology, and have a typical average size of about 240 nm. By altering the ratio of the two magnetic nanoparticles, the thickness of Ni shells can be adjusted. Oleic acid ligands are crucial for the formation of core-shell structure. Magnetic analysis suggests that core-shell superparticles display dual-phase magnetic interactions, contrasting with the single-phase magnetic behaviors of commonly core-shell magnetic nanoparticles. The calculation on the effective magnetic anisotropy constants indicates that the presence of Ni shell layers reduces the dipole interactions among the Mn3O4 core particles. Due to the presence of Ni nanoparticle shells, the blocking temperature of Mn3O4 is reduced, while the Curie temperature of Mn3O4 is independent on Ni content. Tunable magnetic properties can be achieved by modulating the Ni nanoparticle shell thickness. This study offers insights for the development of core-shell superparticles with varied magnetic characteristics.
摘要：
通过自组装两种不同类型的纳米颗粒形成的二元超颗粒可以利用协同相互作用并产生先进的多功能材料。具有核壳结构的双磁超粒子由于其特定的空间构型而具有独特的性质。在这里，我们通过乳液自组装技术构建了Mn3O4@Ni核壳二元超粒子。产生的超粒子具有球形形态，并且具有约240nm的典型平均尺寸。通过改变两种磁性纳米粒子的比例，镍壳的厚度可以调整。油酸配体对于形成核-壳结构至关重要。磁性分析表明，核壳超粒子表现出双相磁相互作用，与通常的核-壳磁性纳米粒子的单相磁性行为形成对比。对有效磁各向异性常数的计算表明，Ni壳层的存在降低了Mn3O4核颗粒之间的偶极相互作用。由于镍纳米粒子壳的存在，Mn3O4的阻塞温度降低，而Mn3O4的居里温度与Ni含量无关。可调谐的磁性可以通过调节Ni纳米颗粒壳厚度来实现。这项研究为具有不同磁特性的核壳超粒子的发展提供了见解。
