Incorporation of Sc into the structure of barium-hexaferrite nanoplatelets and its extraordinary finite-size effect on the magnetic properties

Makovec, Darko; Komelj, Matej; Dražić, Goran; Belec, Blaž; Goršak, Tanja; Gyergyek, Sašo; Lisjak, Darja

doi:10.1016/j.actamat.2019.04.050

Cited by 26 publications

(24 citation statements)

References 46 publications

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“…The morphology and crystals structure of the platelets was verified with a transmission electron microscope (TEM, Jeol 2100). The thickness of the platelets was predominately 3 nm and 4.1 nm, and 5.3 nm 30,31 . The distribution of the platelet diameter is approximately lognormal, with a mean of 29 nm and a standard deviation of 13 nm as was estimated from equivalent diameter using DigitalMicrograph ™ Gatan Inc. software.…”

Section: Synthesis and Preparation Of Suspensionsmentioning

confidence: 99%

Evolution of nematic and ferromagnetic ordering in suspensions of magnetic nanoplatelets

et al. 2019

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Suspensions of magnetic nanoplatelets in isotropic solvents are very interesting examples of ferrofluids. It has been shown that above a certain concentration ΦNI such suspensions form a ferromagnetic nematic phase, which makes this system a unique example of a dipolar fluid. The formation of a nematic phase is driven by anisotropic electrostatic and long-range dipolar magnetic interactions. Here, we present studies of the evolution of short range positional and orientational magnetic order in the suspensions with volume fractions below and above ΦNI, using small angle neutron scattering (SANS). The results show that in the absence of an external magnetic field, short range positional and orientational order already exist at relatively low volume fractions. Polarized SANS revealed that the contribution of ferromagnetic ordering to the formation of the nematic phase is significant. The ferromagnetic correlations can be qualitatively explained by a simple model, which takes into account anisotropic screened electrostatic and dipolar magnetic interactions.

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Section: Synthesis and Preparation Of Suspensionsmentioning

confidence: 99%

Evolution of nematic and ferromagnetic ordering in suspensions of magnetic nanoplatelets

et al. 2019

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“…All new applications are based on systems of fully dispersed barium hexaferrite NPLs partly substituted with Sc 3+ (BSHF), ensuring applicable magnetic properties of very thin (3-5 nm) NPLs with diameters of 20-100 nm [9,10]. BSHF NPLs were dispersed at the highest concentrations in 1-butanol when stabilized by dodecylbenzene sulfonic acid (DBSA) [3,11].…”

Section: Introductionmentioning

confidence: 99%

New Insights into Amino-Functionalization of Magnetic Nanoplatelets with Silanes and Phosphonates

et al. 2022

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Magnetic nanoplatelets (NPLs) based on barium hexaferrite (BaFe12O19) are suitable for many applications because of their uniaxial magneto-crystalline anisotropy. Novel materials, such as ferroic liquids, magneto-optic composites, and contrast agents for medical diagnostics, were developed by specific surface functionalization of the barium hexaferrite NPLs. Our aim was to amino-functionalize the NPLs’ surfaces towards new materials and applications. The amino-functionalization of oxide surfaces is challenging and has not yet been reported for barium hexaferrite NPLs. We selected two amine ligands with two different anchoring groups: an amino-silane and an amino-phosphonate. We studied the effect of the anchoring group, backbone structure, and processing conditions on the formation of the respective surface coatings. The core and coated NPLs were examined with transmission electron microscopy, and their room-temperature magnetic properties were measured. The formation of coatings was followed by electrokinetic measurements, infrared and mass spectroscopies, and thermogravimetric analysis. The most efficient amino-functionalization was enabled by (i) amino-silanization of the NPLs precoated with amorphous silica with (3-aminopropyl)triethoxysilane and (ii) slow addition of amino-phosphonate (i.e., sodium alendronate) to the acidified NPL suspension at 80 °C.

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“…SEM images of the BaFe

and Fe

particle clusters are presented in Figure 8 and Figure 9 , respectively. A magnification of 40,000× (see the right-hand pictures) depicts the hexagonal structure of the BaFe

particles [ 37 ] and roundish shape of the Fe

nanoparticles [ 38 ]. Individual Fe

nanoparticles were more homogeneous in size than individual BaFe

particles, which were polydisperse hexagonal flakes, according to their datasheets.…”

Section: Resultsmentioning

confidence: 99%

Optical Imaging of Magnetic Particle Cluster Oscillation and Rotation in Glycerol

et al. 2021

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Magnetic particles have been evaluated for their biomedical applications as a drug delivery system to treat asthma and other lung diseases. In this study, ferromagnetic barium hexaferrite (BaFe12O19) and iron oxide (Fe3O4) particles were suspended in water or glycerol, as glycerol can be 1000 times more viscous than water. The particle concentration was 2.50 mg/mL for BaFe12O19 particle clusters and 1.00 mg/mL for Fe3O4 particle clusters. The magnetic particle cluster cross-sectional area ranged from 15 to 1000 μμm2, and the particle cluster diameter ranged from 5 to 45 μμm. The magnetic particle clusters were exposed to oscillating or rotating magnetic fields and imaged with an optical microscope. The oscillation frequency of the applied magnetic fields, which was created by homemade wire spools inserted into an optical microscope, ranged from 10 to 180 Hz. The magnetic field magnitudes varied from 0.25 to 9 mT. The minimum magnetic field required for particle cluster rotation or oscillation in glycerol was experimentally measured at different frequencies. The results are in qualitative agreement with a simplified model for single-domain magnetic particles, with an average deviation from the model of 1.7 ± 1.3. The observed difference may be accounted for by the fact that our simplified model does not include effects on particle cluster motion caused by randomly oriented domains in multi-domain magnetic particle clusters, irregular particle cluster size, or magnetic anisotropy, among other effects.

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Incorporation of Sc into the structure of barium-hexaferrite nanoplatelets and its extraordinary finite-size effect on the magnetic properties

Cited by 26 publications

References 46 publications

Evolution of nematic and ferromagnetic ordering in suspensions of magnetic nanoplatelets

Evolution of nematic and ferromagnetic ordering in suspensions of magnetic nanoplatelets

New Insights into Amino-Functionalization of Magnetic Nanoplatelets with Silanes and Phosphonates

Optical Imaging of Magnetic Particle Cluster Oscillation and Rotation in Glycerol

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