NABLA Lab, Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
Molecules. 2020 Mar 9;25(5):1234. doi: 10.3390/molecules25051234.
The capability of synthesizing specific nanoparticles (NPs) by varying their shape, size and composition in a controlled fashion represents a typical set of engineering tools that tune the NPs magnetic response via their anisotropy. In particular, variations in NP composition mainly affect the magnetocrystalline anisotropy component, while the different magnetic responses of NPs with isotropic (i.e., spherical) or elongated shapes are mainly caused by changes in their shape anisotropy. In this context, we propose a novel route to obtain monodispersed, partially hollow magnetite nanorods (NRs) by colloidal synthesis, in order to exploit their shape anisotropy to increase the related coercivity; we then modify their composition via a cation exchange (CE) approach. The combination of a synthetic and post-synthetic approach on NRs gave rise to dramatic variations in their magnetic features, with the pores causing an initial magnetic hardening that was further enhanced by the post-synthetic introduction of a manganese oxide shell. Indeed, the coupling of the core and shell ferrimagnetic phases led to even harder magnetic NRs.
通过控制其形状、大小和组成来合成特定纳米颗粒（NPs）的能力代表了一组典型的工程工具，通过各向异性来调整 NPs 的磁响应。特别是，NP 组成的变化主要影响磁晶各向异性分量，而各向同性（即球形）或拉长形状的 NPs 的不同磁响应主要是由于它们的形状各向异性的变化引起的。在这种情况下，我们提出了一种通过胶体合成获得单分散、部分空心磁铁矿纳米棒（NRs）的新途径，以利用其形状各向异性来提高相关矫顽力；然后通过阳离子交换（CE）方法来修饰它们的组成。NRs 上的合成和后合成方法的结合导致了它们磁性能的显著变化，孔导致了初始的磁硬化，而后合成引入的氧化锰壳进一步增强了这种硬化。事实上，核心和壳铁磁相的耦合导致了更硬的磁性 NRs。
