Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition
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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 that fcc-to-fct conversion does occur, we also reveal the formation of silicide, which can prevent the stronger magnetic properties of fct-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.
Chen , S , Lee , S L & André , P 2016 , ' Silicide induced surface defects in FePt nanoparticle fcc -to- fct thermally activated phase transition ' Journal of Magnetism and Magnetic Materials , vol 417 , pp. 442-450 . DOI: 10.1016/j.jmmm.2016.05.099
Journal of Magnetism and Magnetic Materials
© 2016, Elsevier BV. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at www.sciencedirect.com / https://dx.doi.org/10.1016/j.jmmm.2016.05.099
The authors would like to thank the James and Enid Nicol Trust for funding SC's studentship, the Canon Foundation in Europe for supporting PA's visits at the RIKEN and his Fellowship, and the Ministry of Science, ICT & Future Planning, Korea (201000453, 2015001948, 2014M3A6B3063706) for hosting PA's visits during the final write-up and submission stages of the manuscript.
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