Structure and magnetism of ultra-small cobalt particles assembled at titania surfaces by ion beam synthesis

Simple item page
dc.contributor.authorBake, Aen_AU
dc.contributor.authorRezoanur Rahman, Men_AU
dc.contributor.authorEvans, PJen_AU
dc.contributor.authorCortie, MBen_AU
dc.contributor.authorNancarrow, Men_AU
dc.contributor.authorAbrudan, Ren_AU
dc.contributor.authorRadu, Fen_AU
dc.contributor.authorKhaydukov, Yen_AU
dc.contributor.authorCauser, GLen_AU
dc.contributor.authorCallori, SJen_AU
dc.contributor.authorLivesey, KLen_AU
dc.contributor.authorMitchell, DRGen_AU
dc.contributor.authorPastuovic, Zen_AU
dc.contributor.authorWang, XLen_AU
dc.contributor.authorCortie, DLen_AU
dc.date.accessioned2024-12-12T22:16:41Zen_AU
dc.date.available2024-12-12T22:16:41Zen_AU
dc.date.issued2021-12en_AU
dc.date.statistics2024-05-28en_AU
dc.description.abstractMetallic cobalt nanoparticles offer attractive magnetic properties but are vulnerable to oxidation, which suppresses their magnetization. In this article, we report the use of ion beam synthesis to produce ultra-small, oxidation-resistant, cobalt nanoparticles embedded within substoichiometric TiO2-δ thin films. Using high fluence implantation of cobalt at 20–60 keV, the particles were assembled with an average size of 1.5 ± 1 nm. The geometry and structure of the nanoparticles were studied using scanning transmission electron microscopy. Near-edge X-ray fluorescence spectroscopy on the L2,3 Co edges confirms that the majority of the particles beneath the surface are metallic, unoxidised cobalt. Further evidence of the metallic nature of the small particles is provided via their high magnetization and superparamagnetic response between 3 and 300 K with a low blocking temperature of 4.5 K. The magnetic properties were studied using a combination of vibrating sample magnetometry, element-resolved X-ray magnetic circular dichroism, and depth-resolved polarised neutron reflectometry. These techniques provide a unified picture of the magnetic metallic Co particles. We argue, based on these experimental observations and thermodynamic calculations, that the cobalt is protected against oxidation beneath the surface of titania owing to the enthalpic stability of TiO2 over CoO which inhibits solid state reactions. Crown Copyright © 2021 Published by Elsevier B.V.en_AU
dc.description.sponsorshipDC acknowledges the support of the Australian Research Council (ARC) via DE180100314 and UOW-ANSTO seed grant. This work was partly supported by the ARC Centre for Excellence in Future Low Energy Electronics (CE170100039). This research used the JEOL JEM-ARM200F funded by the ARC LIEF grant (LE120100104). Ion beam implantation was performed using the facilities at the Centre for Accelerator Science (CAS), at the Australian Nuclear Science and Technology Organisation (P7437). Research activities at the CAS including operation of the LEII/accelerator systems are funded by the NCRIS program by the Australian Government. Part of this research was undertaken on the Soft X-ray spectroscopy beamline at the BESSY, Helmholtz Zentrum, Berlin. Travel support was provided by the Australian Synchrotron’s International Access Funding Program. This work is partially based on experiments performed at the NREX instrument operated by Max-Planck Society at the Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany. YK would like to acknowledge financial support of German Research Foundation (Deutsche Forschungsgemeinschaft, DFG, Project No. 107745057 - TRR80). AB acknowledges the support of an post-graduate research award from the Australian Institute of Nuclear Science and Engineering (AINSE).en_AU
dc.identifier.articlenumber151068en_AU
dc.identifier.citationBake, A., Rezoanur Rahman, M., Evans, P. J., Cortie, M. B., Nancarrow, M., Abrudan, R., Radu, F., Khaydukov, Y., Causer, G. L., Callori, S. J., Livesey, K. L., Mitchell, D. R. G., Pastuovic, Z., Wang, X., & Cortie, D. l. (2021). Structure and magnetism of ultra-small cobalt particles assembled at titania surfaces by ion beam synthesis. Applied Surface Science, 570, 151068. doi.:10.1016/j.apsusc.2021.151068en_AU
dc.identifier.issn0169-4332en_AU
dc.identifier.journaltitleApplied Surface Scienceen_AU
dc.identifier.pagination151068-en_AU
dc.identifier.urihttps://doi.org/10.1016/j.apsusc.2021.151068en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15817en_AU
dc.identifier.volume570en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectIon beamsen_AU
dc.subjectSynthesisen_AU
dc.subjectCobalten_AU
dc.subjectMagnetismen_AU
dc.subjectParticlesen_AU
dc.subjectThin Filmsen_AU
dc.subjectElectron microscopyen_AU
dc.subjectTransmissionen_AU
dc.titleStructure and magnetism of ultra-small cobalt particles assembled at titania surfaces by ion beam synthesisen_AU
dc.typeJournal Articleen_AU
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
1-s2.0-S0169433221021255-main.pdf
Size:
8.08 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.66 KB
Format:
Plain Text
Description:
Download
Collections
Journal Articles