Electrostatic Interactions between Barium Hexaferrite Nanoplatelets in Alcohol Suspensions

Boštjančič, Patricija Hribar; Tomšič, Matija; Jamnik, Andrej; Lisjak, Darja; Mertelj, Alenka

doi:10.1021/acs.jpcc.9b07455

Cited by 15 publications

(7 citation statements)

References 27 publications

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“…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]. BSHF NPLs were also successfully electrostatically stabilized in water by modifying their surface with citric acid or amorphous silica or phosphonate coatings [5,13,14].…”

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2022

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“…Thus, an issue of the influence of a magnetic field and shear flow on the MVE in barium hexaferrite MFs is definitely not sufficiently studied. Although, magnetic and structural properties of such ferrofluids, as well as various methodological issues of synthesis of corresponding nanoplates and their physical and chemical properties have been studied in detail, for example, in [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ], therefore, they are not a priority objective of this study.…”

Section: Introductionmentioning

confidence: 99%

Magnetoviscosity of a Magnetic Fluid Based on Barium Hexaferrite Nanoplates

2021

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This paper presents the results of an experimental study of the influence of an external magnetic field on the shear flow behaviour of a magnetic fluid based on barium hexaferrite nanoplates. With the use of rheometry, the magnetoviscosity and field-dependent yield-stress in the fluid are evaluated. The observed fluid behaviour is compared to that of ferrofluids with magnetic nanoparticles having high dipole interaction. The results obtained supplement the so-far poorly studied topic of the influence of magnetic nanoparticles’ shape on magnetoviscous effects. It is concluded that the parameter determining the observed magnetoviscous effects in the fluid under study is the ratio V2/l3, where V is the volume of the nanoparticle and l is the size of the nanoparticle in the direction corresponding to its orientation in the externally applied magnetic field.

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“…In contrast, the width distribution is broad but can be narrowed by a partial Sc(III) substitution for Fe(III) . The Sc-substituted BHF NPLs retain the uniaxial magneto-crystalline anisotropy, high sensitivity to magnetic field, and surface chemistry, and they can be electro(-sterically) stabilized in water and alcohols. ,, …”

Section: Introductionmentioning

confidence: 99%

Formation of Fe(III)-phosphonate Coatings on Barium Hexaferrite Nanoplatelets for Porous Nanomagnets

et al. 2020

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Amorphous coatings formed with mono-, di-, and tetra-phosphonic acids on barium hexaferrite (BHF) nanoplatelets using various synthesis conditions. The coatings, synthesized in water with di-or tetra-phosphonic acids, were thicker than that could be expected from the ligand size and the surface coverage, as determined by thermogravimetric analysis. Here, we propose a mechanism for coating formation based on direct evidence of the surface dissolution/precipitation of the BHF nanoplatelets. The partial dissolution of the nanoplatelets was observed with atomic-resolution scanning transmission electron microscopy, and the released Fe(III) ions were detected with energy-dispersive Xray spectroscopy and electron energy loss spectroscopy in amorphous coating. The strong chemical interaction between the surface Fe(III) ions with phosphonic ligands induces the dissolution of BHF nanoplatelets and the consequent precipitation of the Fe(III)-phosphonates that assemble into a porous coating. The so-obtained porous nanomagnets are highly responsive to a very weak magnetic field (in the order of Earth's magnetic field) at room temperature, which is a major advantage over the classic mesoporous nanomaterials and metal−organo-phosphonic frameworks with only a weak magnetic response at a few kelvins. The combination of porosity with the intrinsic magneto-crystalline anisotropy of BHF can be exploited, for example, as sorbents for heavy metals from contaminated water.

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Electrostatic Interactions between Barium Hexaferrite Nanoplatelets in Alcohol Suspensions

Cited by 15 publications

References 27 publications

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

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

Magnetoviscosity of a Magnetic Fluid Based on Barium Hexaferrite Nanoplates

Formation of Fe(III)-phosphonate Coatings on Barium Hexaferrite Nanoplatelets for Porous Nanomagnets

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