Unraveling agglomeration and deagglomeration in aqueous colloidal dispersions of very small tin dioxide nanoparticles

Mackert, Viktor; Schroer, Martin A.; Winterer, Markus

doi:10.1016/j.jcis.2021.10.194

Cited by 8 publications

(5 citation statements)

References 79 publications

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“…In more detail, the short axis of these elongated clusters is pointing toward the LC director, indicating an orientational coupling between the LC matrix and MNP clusters. The different shapes of the clusters are expected to be a consequence of the (de-)aggregation process, which is dependent on the interparticle interactions, particle concentrations, and external perturbations, the last being induced by the dilution process ( Mackert et al., 2021 ). As samples LC1 to LC4 have been prepared by dilution of the LC5 stock solution, the structural difference can be attributed to de- (LC3, LC4) and re-agglomeration (LC1, LC2) of structure LC5.…”

Section: Resultsmentioning

confidence: 99%

Clustering in ferronematics—The effect of magnetic collective ordering

et al. 2021

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Summary Clustering of magnetic nanoparticles can dramatically change their collective magnetic properties, and it consequently may influence their performance in biomedical and technological applications. Owing to tailored surface modification of magnetic particles such composites represent stable systems. Here, we report ferronematic mixtures that contain anisotropic clusters of mesogen-hybridized cobalt ferrite nanoparticles dispersed in liquid crystal host studied by different experimental methods—magnetization measurements, small-angle X-ray scattering (SAXS), small-angle neutron scattering (SANS), and capacitance measurements. These measurements reveal non-monotonic dependencies of magnetization curves and the Fréedericksz transition on the magnetic nanoparticles concentration. This can be explained by the formation of clusters, whose structures were determined by SAXS measurements. Complementary to the magnetization measurements, SANS measurements of the samples were performed for different magnetic field strengths to obtain information on the orientation of the liquid crystal molecules. We demonstrated that such hybrid materials offer new avenues for tunable materials.

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Section: Resultsmentioning

confidence: 99%

Clustering in ferronematics—The effect of magnetic collective ordering

et al. 2021

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“…This temperature regime allows for substantial dehydration without significant structural changes due to oxygen depletion or sintering . Another part of sample 6p is used to generate an aqueous colloid of SnO 2 in ultrapure water (≥18.2 MΩ cm at 25 °C) at pH 5.5 by ultrasonic agitation to yield sample 6c …”

Section: Methodsmentioning

confidence: 99%

“…19 Another part of sample 6p is used to generate an aqueous colloid of SnO 2 in ultrapure water (≥18.2 MΩ cm at 25 °C) at pH 5.5 by ultrasonic agitation to yield sample 6c. 20 Transmission Electron Microscopy. Samples for TEM investigations are prepared by dispersing 5 mg of the powder in 10 mL of semiconductor-grade methanol and sonication for 5 min.…”

Section: ■ Introductionmentioning

confidence: 99%

Very Small Nanocrystalline Tin Dioxide Particles: Local-, Crystal-, and Micro-Structure

Mackert,

Winter,

Jackson

et al. 2023

J. Phys. Chem. C

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In case of very small nanocrystals, the surface is the dominant defect, generating a microstructure as deviation from the ideal crystal structure by breaking the translational symmetry of the lattice. This heterogeneous disorder may be observed as a different local structure in the core and shell of the nanocrystals and is highly relevant in all properties and applications for which defects are detrimental or beneficial, for example, charge-carrier traps in (opto-)electronics or active surface sites in heterogeneous catalysis. Very small SnO 2 nanocrystals generated by chemical vapor synthesis with coherent diffracting domain sizes between 2 and 13 nm are investigated as a model system since they form phase-pure stannic oxide isostructural to rutile. Local structure, crystal structure, and microstructure are studied using X-ray absorption spectroscopy, wide-angle X-ray scattering, X-ray diffraction, and transmission electron microscopy analyzed using reverse Monte Carlo simulations, Rietveld refinement, and image analysis. Size, surface, and interface effects as well as structural defects are discussed. The fraction of atoms at surfaces is substantial for very small nanoparticles. However, only very subtle structural changes are observed here for very small SnO 2 nanocrystals as revealed by detailed quantitative structural analysis. This may be because the particles are highly crystalline even for the ultrasmall 2 nm particles which are close to the molecular cluster regime.

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“…37 The small grain size of SnO 2 makes it easy to agglomerate. 38,39 As a result, the peak strength of XRD at xAg@SnO 2 /CsPbBr 3 is weakened. The weakened diffraction peaks of CsPbBr 3 at 15.08°, 21.66°, 37.95°, and 30.70°may be attributed to the agglomeration of SnO 2 NPs on CsPbBr 3 .…”

Section: G Characterizationmentioning

confidence: 99%

Ag@SnO2/CsPbBr3 nanocomposite gas sensor for well-behaved low-concentration ethanolamine sensing at room temperature

Xu,

Jiang,

Liu

et al. 2024

Journal of Applied Physics

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It is a novel-effective process for realizing high-efficiency sensing and continuous gas monitoring by introducing precious metals into metal–oxide–semiconductors (MOSs). In this study, Ag is exploited to prepare surface functionalized SnO2 nanoparticles (NPs) and innovative xAg@SnO2/CsPbBr3, activating and catalyzing the gas sensing reactions on semiconductors. The results show that the precious metal Ag NPs promote the directional transport of carriers, thus improving the gas sensing performances. In addition, innovative xAg@SnO2/CsPbBr3 composites originated from Ag@SnO2 NPs and 3-mercaptopropionic acid treated all-inorganic perovskite CsPbBr3 are constructed to further accelerate electron transfer on heterointerfaces, enabling continuous and efficient monitoring of ethanolamine (EA) at room temperature. The sensing properties of Ag@SnO2/CsPbBr3 on various volatile organic compounds are investigated. Compared with pure CsPbBr3, the EA response of as-prepared 2Ag@SnO2/CsPbBr3 is obviously improved by about sevenfold. The response/recovery time is greatly shortened, besides the good stability. Another interesting result for xAg@SnO2/CsPbBr3 is the lower limit of detection of 44.43 ppb. The work demonstrates that Ag modification facilitates the adsorption/desorption rate and the response. Furthermore, the catalytic activation of noble metal Ag NPs and the synergistic interaction of SnO2/CsPbBr3 nano-heterojunctions promote EA sensing performances at room temperature.

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Unraveling agglomeration and deagglomeration in aqueous colloidal dispersions of very small tin dioxide nanoparticles

Cited by 8 publications

References 79 publications

Clustering in ferronematics—The effect of magnetic collective ordering

Clustering in ferronematics—The effect of magnetic collective ordering

Very Small Nanocrystalline Tin Dioxide Particles: Local-, Crystal-, and Micro-Structure

Ag@SnO2/CsPbBr3 nanocomposite gas sensor for well-behaved low-concentration ethanolamine sensing at room temperature

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