1. Saturation magnetisation as an indicator of the disintegration of barium hexaferrite nanoplatelets during the surface functionalisationDarja Lisjak, Iztok Arčon, Matic Poberžnik, Gabriela Herrero‑Saboya, Ali Tufani, Andraž Mavrič, Matjaž Valant, Patricija Hribar Boštjančič, Alenka Mertelj, Darko Makovec, Layla Martin‑Samos, 2023, original scientific article Abstract: Barium hexaferrite nanoplatelets (BHF NPLs) are permanent nanomagnets with the magnetic easy axis aligned perpendicular to their basal plane. By combining this specific property with optimised surface chemistry, novel functional materials were developed, e.g., ferromagnetic ferrofluids and porous nanomagnets. We compared the interaction of chemically different phosphonic acids, hydrophobic and hydrophilic with 1–4 phosphonic groups, with BHF NPLs. A decrease in the saturation magnetisation after functionalising the BHF NPLs was correlated with the mass fraction of the nonmagnetic coating, whereas the saturation magnetisation of the NPLs coated with a tetraphosphonic acid at 80 °C was significantly lower than expected. We showed that such a substantial decrease in the saturation magnetisation originates from the disintegration of BHF NPLs, which was observed with atomic-resolution scanning transmission electron microscopy and confirmed by a computational study based on state-of-the-art first-principles calculations. Fe K-edge XANES (X-ray absorption near-edge structure) and EXAFS (Extended X-ray absorption fine structure) combined with Fourier-transformed infrared (FTIR) spectroscopy confirmed the formation of an Fe–phosphonate complex on the partly decomposed NPLs. Comparing our results with other functionalised magnetic nanoparticles confirmed that saturation magnetisation can be exploited to identify the disintegration of magnetic nanoparticles when insoluble disintegration products are formed.
Keywords: barium hexaferrite, Fe XANES, EXAFS, magnetic nanoparticles
Published in RUNG: 06.07.2023; Views: 3189; Downloads: 8
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2. Magnetic anisotropy of strontium ferrite nanoparticlesCesar de Julian Fernandez, D. Mishra, M. Cabassi, M. Petrecca, M. Albino, M. Suara-Muzquiz, Petra Jenuš, A. Quesada, T. Schliesch, Blaž Belec, C. Sangregorio, F. Albertini, 2019, published scientific conference contribution abstract Keywords: hexaferrite, nanoparticles, magnetic anisotropy, SPD
Published in RUNG: 04.06.2019; Views: 5058; Downloads: 0
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3. Incorporation of Sc into the structure of barium-hexaferrite nanoplatelets and its ex-traordinary finite-size effect on the magnetic propertiesDarko Makovec, Matej Komelj, Goran Dražić, Blaž Belec, Tanja Goršak, Sašo Gyergyek, Darja lisjak, 2019, original scientific article Keywords: Nanoparticles, Magnetic properties, Size effect, Structure properties relationship, Ferrite.
Published in RUNG: 06.05.2019; Views: 4389; Downloads: 0
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7. Bi-magnetic composite nanoplatelets combining hard-magnetic barium hexaferrite core covered with soft magnetic iron oxide layerBlaž Belec, Darko Makovec, Goran Dražić, Benjamin Podmiljšak, Tanja Goršak, Sašo Gyergek, Matej Komelj, Josep Nogues, unpublished invited conference lecture Keywords: bi-magnetic nanoparticles, composite nanoparticles, exchange coupling
Published in RUNG: 05.06.2018; Views: 5282; Downloads: 0
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