Isotropic to nematic transition in alcohol ferrofluids of barium hexaferrite nanoplatelets

Boštjančič, Patricija Hribar; Gregorin, Žiga; Sebastián, Nerea; Osterman, Natan; Lisjak, Darja; Mertelj, Alenka

doi:10.1016/j.molliq.2021.118038

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…Similarly, the phase diagram of hard platelets is well-known and, depending on the aspect ratio and volume fraction, exhibits liquid-crystalline phases 19,20 . There have also been some early computational 21 and experimental 22 investigations of discotic systems, which focus primarily on the orientations and isotropic-to-nematic phase a Faculty of Physics, University of Vienna, Bolzmanngasse 5, Vienna 1090, Austria. E-mail: margaret.rosenberg@univie.ac.at transition of the suspensions.…”

Section: Introductionmentioning

confidence: 99%

The influence of anisotropy on the microstructure and magnetic properties of dipolar nanoplatelet suspensions

Rosenberg

Kantorovich

2023

Phys. Chem. Chem. Phys.

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Section: Introductionmentioning

confidence: 99%

The influence of anisotropy on the microstructure and magnetic properties of dipolar nanoplatelet suspensions

Rosenberg

Kantorovich

2023

Phys. Chem. Chem. Phys.

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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]. The long-range electrostatic repulsion provided by the DBSa double layer was found to be crucial in suppressing the long-range magnetic dipole attraction between ferrimagnetic BSHF NPLs [12].…”

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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“…[ 36 ] The substantial reduction in the critical volume fraction was achieved by excluding smaller platelets and optimizing the parameters of the suspensions, as described previously. [ 46 ] Additional evidence that the observed birefringence was indeed a consequence of spontaneous platelet ordering was the appearance of the so‐called schlieren structure, which is typical for an unaligned nematic, indicating only locally uniform order ( Figure a).…”

Section: Resultsmentioning

confidence: 99%

Spontaneous Chiral Symmetry Breaking and Lane Formation in Ferromagnetic Ferrofluids

Vilfan,

Lampret,

Gregorin

et al. 2023

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Ferromagnetic ferrofluids are synthetic materials consisting of magnetic nanoplatelets dispersed in an isotropic fluid. Their main characteristics are the formation of stable magnetic domains and the presence of macroscopic magnetization even in the absence of a magnetic field. Here, the authors report on the experimental observation of spontaneous stripe formation in a ferromagnetic ferrofluid in the presence of an oscillating external magnetic field. The striped structure is identified as elongated magnetic domains, which exhibit reorientation upon reversal of the magnetic field. The stripes are oriented perpendicular to the magnetic field and are separated by alternating flow lanes. The velocity profile is measured using a space–time correlation technique that follows the motion of the thermally excited fluctuations in the sample. The highest velocities are found in the depleted regions between individual domains and reach values up to several µm s−1. The fluid in adjacent lanes moves in the opposite directions despite the applied magnetic field being uniform. The formation of bidirectional flow lanes can be explained by alternating rotation of magnetic nanoparticles in neighboring stripes, which indicates spontaneous breaking of the chiral symmetry in the sample.

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Isotropic to nematic transition in alcohol ferrofluids of barium hexaferrite nanoplatelets

Cited by 8 publications

References 25 publications

The influence of anisotropy on the microstructure and magnetic properties of dipolar nanoplatelet suspensions

The influence of anisotropy on the microstructure and magnetic properties of dipolar nanoplatelet suspensions

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

Spontaneous Chiral Symmetry Breaking and Lane Formation in Ferromagnetic Ferrofluids

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