Synthesis of iron oxide nanoparticles coated in silica to form a protective Fe ₃ O ₄ @SiO ₂ core/shell structure Patrycja Edyta Rose 1 , Md Towhidul Islam 2 , Gavin Mountjoy 2 , Anna Corrias 1 1 School of Chemistry and Forensic Science, University of Kent, UK, 2 School of Physics and Astronomy, University of Kent, UK Magnetic nanoparticles have become a popular field of study due to their wide variety of applications, such as batteries, bio-medicine, and storage media.[1] Among those, Fe 3 O 4 (magnetite) nanoparticles are widely focused on. However, these are prone to oxidisation, forming gamma-Fe 2 O 3 (maghemite).[2] To overcome this, Fe 3 O 4 nanoparticles can be coated with a protective layer, such as amorphoussilica, forming a core-shell structure.[3]In this study, magnetite nanoparticles were synthesised via the co-precipitation method, due to its high yield and use of inexpensive materials. The particles were then coated with silica using a ‘sol-gel’ method. Both bare and coated nanoparticle samples are magnetic. Characterisation was done using Powder XRD analysis, TEMimaging, and XRF analysis. All prepared samples displayed characteristic Fe 3 O 4 peaks within the XRD pattern, with coated samples also showing a broad halo in the region of 20-30° 2θ, indicating the presence of amorphous silica. The average sizeof the Fe 3 O 4 nanocrystals was calculated with the Scherrer equation, showing nanocrystals to be in the 13 nm range, in both bare and coated samples. TEM imaging showed particles were spherical in shape for both types of sample. Silica coatings were further evidenced by XRF, which indicated silica content of around 30% relative to iron oxide.The effect of different nanoparticle synthesis methods (to attain a product of monodisperse size and shape), and different coating methods (to achieve an evencoating of individual nanoparticles) will be discussed. The possibility of dispersing the coated samples into a glass matrix will also be explored. References 1. S. F. Hasany; I. Ahmed; J. Rajan; A. Rehman. Systematic Review of the Preparation Techniques of Iron Oxide Magnetic Nanoparticles. Nanosci. Nanotechnol. 2012, 6. 2. N. Saxena; M. Singhb. Efficient Synthesis of Superparamagnetic Magnetite Nanoparticles under Air for Biomedical Applications. J. Magn. Magn. Mater. 2017, 429. 3. K. Qiao; W. Tian; J. Bai; L. Wang; J. Zhao; Z. Du; X. Gong. Application of Magnetic Adsorbents Based on Iron Oxide Nanoparticles for Oil Spill Remediation: A Review. J. Taiwan Inst. Chem. Eng. 2019, 97.
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