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: 2008; Downloads: 7
 Full text (3,60 MB)
This document has many files! More... |
2. |
3. A novel functionalization strategy for the dispersion of permanently magnetic barium-hexaferrite nanoplatelets in biological mediaTanja Goršak, Darko Makovec, Uroš Javornik, Blaž Belec, Slavko Kralj, Darja Lisjak, 2019, published scientific conference contribution abstract Keywords: colloidal stability, magnetic, nanoplatelet, biological media, dextran
Published in RUNG: 30.09.2019; Views: 4449; Downloads: 0
This document has many files! More... |
4. |
5. 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: 3759; Downloads: 0
This document has many files! More... |
6. |
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: 4442; Downloads: 0
This document has many files! More... |
8. Biotransformation of copper oxide nanoparticles by the pathogenic fungus Botrytis cinereaEva Kovačec, Marjana Regvar, Johannes Teun van Elteren, Iztok Arčon, Tamás Papp, Darko Makovec, Katarina Vogel-Mikuš, 2017, original scientific article Abstract: Two plant pathogenic fungi, Botrytis cinerea and Alternaria alternata, isolated from crop plants, were
exposed to Cu in ionic (Cu2þ), microparticulate (MP, CuO) or nanoparticulate (NP, Cu or CuO) form, in
solid and liquid culturing media in order to test fungal response and toxic effects of the mentioned
compounds for the potential use as fungicides. B. cinerea has shown pronounced growth and lower levels
of lipid peroxidation compared to A. alternata. Its higher resistance/tolerance is attributed mainly to
biotransformation of CuO and Cu NPs and CuO MPs into a blue compound at the fungal/culturing media
interface, recognized by Cu K-edge EXAFS analysis as Cu-oxalate complex. The pronounced activity of
catechol-type siderophores and organic acid secretion in B. cinerea induce leaching and mobilization of
Cu ions from the particles and their further complexation with extracellularly secreted oxalic acid. The
ability of pathogenic fungus to biotransform CuO MPs and NPs hampers their use as fungicides. However
the results show that B. cinerea has a potential to be used in degradation of Cu(O) nanoparticles in
environment, copper extraction and purification techniques.
Keywords: copper, metal oxide nanoparticles, detoxification mechanisms, metal pollution, Cu-oxalate
Published in RUNG: 23.08.2017; Views: 4857; Downloads: 0
This document has many files! More... |
