Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition
Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition
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DOI：
10.1016/j.jmmm.2016.05.099
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发表时间：
2016-02
影响因子：
2.7
通讯作者：
Shu Chen;Stephen Lee;P. André;P. André
中科院分区：
文献类型：
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作者：
Shu Chen;Stephen Lee;P. André;P. André
磁性纳米颗粒 (MnP) 涉及广泛的应用，包括高密度信息存储和磁共振成像等。在可用于制备 MnP 的材料中，FePt 正引起越来越多的关注。然而，为了获得 FePt MnP 最强的磁性，通常需要进行热退火，将合成的 nP 面心立方转变为四方相。很少有人讨论这种处理对磁性的潜在副作用。在本研究中，我们重点关注在热退火过程中克服 MnP 聚结策略中常用的二氧化硅壳的影响。虽然我们证明这种壳确实可以防止烧结，并且确实会发生 fcc 到 fct 的转换，但我们还揭示了硅化物的形成，这可以阻止 offct-FePt MnP 的更强磁性完全实现。因此，本报告揭示了对 MnP 热退火过程中发生的界面现象的研究和理解不足，并通过这样做，还强调了开发新策略以避免硅化物形成的好处。
Magnetic nanoparticles (MnPs) are relevant to a wide range of applications including high density information storage and magnetic resonance imaging to name but a few. Among the materials available to prepare MnPs, FePt is attracting growing attention. However, to harvest the strongest magnetic properties of FePt MnPs, a thermal annealing is often required to convert face-centered cubic as synthesized nPs into its tetragonal phase. Rarely addressed are the potential side effects of such treatments on the magnetic properties. In this study, we focus on the impact of silica shells often used in strategies aiming at overcoming MnP coalescence during the thermal annealing. While we show that this shell does prevent sintering, and thatfcc-to-fctconversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties offct-FePt MnPs from being fully realised. This report therefore sheds lights on poorly investigated and understood interfacial phenomena occurring during the thermal annealing of MnPs and, by doing so, also highlights the benefits of developing new strategies to avoid silicide formation.