Dynamic Colloidal Stabilization by Nanoparticle Halos

Karanikas, S.; Louis, Ard A.

doi:10.1103/physrevlett.93.248303

Cited by 59 publications

(79 citation statements)

References 19 publications

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“…While the general trends observed in Ref. [13] are certainly encouraging, we note that there are also important quantitative discrepancies with the experimental [2] and simulational [8] findings. Various calculations in Ref.…”

Section: Comparison To Integral-equation Theorymentioning

confidence: 56%

“…Various calculations in Ref. [13] employ a Debye screening length of λ = 5.0σ nano , much larger than the experimental value λ ≈ 0.33σ nano and, incidentally, rather close to the choice of Chávez et al [12]. This increases the mutual repulsion between nanoparticles, to the extent where it may alter the mechanism responsible for the observed stabilization.…”

Section: Comparison To Integral-equation Theorymentioning

confidence: 99%

“…The system studied in this paper has also been investigated by means of integral-equation theory [12,13], in which the effective colloidal pair potential V eff micro is computed using the two-component Ornstein-Zernike (OZ) equations supplemented with the hypernetted-chain (HNC) closure. Chávez et al [12] were the first to demonstrate that, under the appropriate conditions, the electrostatic repulsion between nanoparticles alone is sufficient to cause the formation of a nanoparticle monolayer on the microsphere surface.…”

Section: Comparison To Integral-equation Theorymentioning

confidence: 99%

“…In this article, we present a detailed technical account of the calculations reported in Ref. [8] and make a comparison with results obtained in an integral-equation study of the same system [12,13,14].…”

Section: Introductionmentioning

confidence: 99%

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Colloidal stabilization via nanoparticle halo formation

Liu

Luijten

2005

Phys. Rev. E

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We present a detailed numerical study of effective interactions between micron-sized silica spheres, induced by highly charged zirconia nanoparticles. It is demonstrated that the effective interactions are consistent with a recently discovered mechanism for colloidal stabilization. In accordance with the experimental observations, small nanoparticle concentrations induce an effective repulsion that counteracts the intrinsic van der Waals attraction between the colloids and thus stabilizes the suspension. At higher nanoparticle concentrations an attractive potential is recovered, resulting in reentrant gelation. Monte Carlo simulations of this highly size-asymmetric mixture are made possible by means of a geometric cluster Monte Carlo algorithm. A comparison is made to results obtained from the Ornstein-Zernike equations with the hypernetted-chain closure.

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Section: Comparison To Integral-equation Theorymentioning

confidence: 56%

Section: Comparison To Integral-equation Theorymentioning

confidence: 99%

Section: Comparison To Integral-equation Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Colloidal stabilization via nanoparticle halo formation

Liu

Luijten

2005

Phys. Rev. E

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“…This phenomenon is attributed to the interplay between electrostatic and van der Waals interactions between the particles and ensures colloidal stability of the suspension [1][2][3][4]. However, in such systems, the cloud thickness is only a few nanometers [5], that allows maintaining a good dispersion state of the suspension only within a narrow range of concentrations of both species.…”

Section: Introductionmentioning

confidence: 99%

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

et al. 2014

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When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50µm) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces -the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter α ≥2), the Brownian motion seems not to affect the cloud behavior.

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TiO₂ Colloid‐Spray Coated Electron‐Transporting Layers for Efficient Perovskite Solar Cells

Paik

Lee

Yun

et al. 2020

Advanced Energy Materials

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it provides a larger contact area between the TiO 2 and perovskite. Almost all of the best PSC efficiencies published so far have been obtained by using TiO 2 photoelectrodes. [15-18] Moreover, excellent long-term photo-stability has also been reported in PSCs fabricated using TiO 2 electrodes. [19] mp-TiO 2 layers for PSCs can be formed using spin-coating or screen-printing methods with TiO 2 pastes containing organic binders and surfactants (e.g., ethyl cellulose and terpineol), as well as organic solvents. [20,21] Subsequently, the TiO 2 layers require a follow-up such as high-temperature process to burn out the organic components contained in the TiO 2 paste. The biggest advantage of a hightemperature process would be a lowering of the series resistance of the layer, due to the strong contact between the TiO 2 particles and the TCO substrate. Therefore, in terms of efficiency, high-temperature-processed TiO 2 layers are very desirable; nevertheless, their use may be a large limiting factor in the fabrication of PSCs using a low-temperature continuous coating process or substrates based on an organic material (e.g., polyethylene naphthalate (PEN)). [22] Even PEN-based flexible substrates can be problematic, because they can bend if subjected to a heat treatment at 150 °C. Although recent studies have shown that SnO 2 can be used as an ETLs to fabricate PSCs at relatively low temperature, a heat treatment at temperature ≥150 °C is required to reach the best performances. [23,24] Meanwhile, formamidinium lead triiodide (FAPbI 3)-based perovskites are generally heat-treated at 150 °C to obtain an α-phase. If all the processes for high-efficiency PSCs can be conducted at ≈100 °C, their value will be very high in terms of using flexible substrates and facilitating large-area continuous processes. Currently, most high-efficiency PSCs are fabricated using spin coating, a simple and reliable technique that can produce very uniform thin films. However, since it is problematic to apply spin coating in large-area processes, other methods including blade coating, [25] slot die coating, [26] inkjet printing, [27] and spray coating [28] have been actively studied as scalable deposition techniques. Among these, spray coating has been already widely used in several industry fields and offers great advantages for the continuous production of PSC modules with large areas and a reduced material consumption. [29] So far, several groups reported the deposition of perovskite thin films or of entire ETLs, perovskites, and HTLs (required for the fabrication TiO 2 is one of the most efficient and widely used materials for electrontransporting layer (ETLs) in perovskite solar cells (PSCs). The formation of efficient TiO 2 layers is generally carried out at high temperature by baking at a temperature >400 °C or by vacuum deposition (e.g., atomic layer deposition and E-beam). In this study, the preparation of a TiO 2 ETL for PSCs is reported with excellent properties at low temperatures based on the synthesis of a stable TiO 2 colloidal ...

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Dynamic Colloidal Stabilization by Nanoparticle Halos

Cited by 59 publications

References 19 publications

Colloidal stabilization via nanoparticle halo formation

Colloidal stabilization via nanoparticle halo formation

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

TiO₂ Colloid‐Spray Coated Electron‐Transporting Layers for Efficient Perovskite Solar Cells

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Dynamic Colloidal Stabilization by Nanoparticle Halos

Cited by 59 publications

References 19 publications

Colloidal stabilization via nanoparticle halo formation

Colloidal stabilization via nanoparticle halo formation

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

TiO2 Colloid‐Spray Coated Electron‐Transporting Layers for Efficient Perovskite Solar Cells

Contact Info

Product

Resources

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TiO₂ Colloid‐Spray Coated Electron‐Transporting Layers for Efficient Perovskite Solar Cells