Early stages of Ostwald ripening

Shneidman, Vitaly A.

doi:10.1103/physreve.88.010401

Cited by 25 publications

(20 citation statements)

References 19 publications

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“…This unambiguously implies that the IP and OP relaxation is governed by the same underlying processes. While the simple exponential fit to the time-evolution of the resistivity relaxation should be considered to be an approximation for describing the Ostwald ripenening nucleated growth process4041, the fact that the IP relaxation process is better described with a stretch exponential fit20, indicates that the microscopic details of the OP relaxation are actually simpler than IP, with a single dominant energy scale given by E R . On the other hand, the distinct steps in the relaxation process are ascribed to the relaxation of complete rows of polarons at a time as recently observed by STM16.…”

Section: Discussionmentioning

confidence: 99%

Three-dimensional resistivity and switching between correlated electronic states in 1T-TaS2

Svetin

Vaskivskyi

Brazovskiǐ

et al. 2017

Sci Rep

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Recent demonstrations of controlled switching between different ordered macroscopic states by impulsive electromagnetic perturbations in complex materials have opened some fundamental questions on the mechanisms responsible for such remarkable behavior. Here we experimentally address the question of whether two-dimensional (2D) Mott physics can be responsible for unusual switching between states of different electronic order in the layered dichalcogenide 1T-TaS2, or it is a result of subtle inter-layer “orbitronic” re-ordering of its stacking structure. We report on in-plane (IP) and out-of-plane (OP) resistance switching by current-pulse injection at low temperatures. Elucidating the controversial theoretical predictions, we also report on measurements of the anisotropy of the electrical resistivity below room temperature. From the T-dependence of ρ⊥ and ρ||, we surmise that the resistivity is more consistent with collective motion than single particle diffusive or band-like transport. The relaxation dynamics of the metastable state for both IP and OP electron transport are seemingly governed by the same mesoscopic quantum re-ordering process. We conclude that 1T-TaS2 shows resistance switching arising from an interplay of both IP and OP correlations.

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Section: Discussionmentioning

confidence: 99%

Three-dimensional resistivity and switching between correlated electronic states in 1T-TaS2

Svetin

Vaskivskyi

Brazovskiǐ

et al. 2017

Sci Rep

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“…219 In fact, it seems that there has been little consideration of the appropriate "complete" specification of initial conditions (not just the initial NC size distribution, but information on the spatial distribution, and correlations between NC size and the local environment). 9,88 To provide a unified description of coarsening which will allow assessment of the dominant pathway and possible crossover behavior, we adopt a more complete (but approximate 220 ) description of temporal evolution than the above simple scaling laws. For either OR or SR, the time evolution of the mean NC "radius", Rav(t), is written as…”

Section: General Issues For or And Sr Including Crossovermentioning

confidence: 99%

Reshaping, Intermixing, and Coarsening for Metallic Nanocrystals: Nonequilibrium Statistical Mechanical and Coarse-Grained Modeling

et al. 2019

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Self-assembly of ensembles of supported 2D or 3D nanoclusters (NCs) by surface deposition, and of unsupported 3D NCs by solution-phase synthesis, produces intrinsically nonequilibrium systems. Individual nanoclusters can have far-from-equilibrium shapes and composition profiles. The free energy of the ensemble can be lowered by coarsening which can involve Ostwald ripening or Smoluchowski ripening (NC diffusion and coalescence). Preservation of individual NC structure and inhibition of coarsening is key for, e.g., avoiding catalyst degradation. In this review, we focus on crystalline metallic NCs. Atomistic-level modeling of equilibration processes typically utilizes stochastic lattice-gas models to access appropriate time-and length-scales. However, predictive modeling requires incorporation of realistic rates for relaxation mechanisms, e.g., periphery diffusion and intermixing, in numerous local environments (rather than the use of generic prescriptions). Alternative coarse-grained modeling must also incorporate appropriate mechanisms and kinetics. At the level of individual NCs, we present analyses of reshaping, including sintering and pinch-off, and of compositional evolution. We also discuss modeling of coarsening including diffusion and decay of individual NCs, and unconventional coarsening processes. We describe high-level modeling integrated with STM studies for 2D epitaxial NCs, and developments in modeling for supported and unsupported 3D NCs motivated by in situ TEM studies.

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“…units to S 8(nano) or S 8(sol) . Coarsening would then be governed by some combination of Ostwald ripening or aggregation [ 40 ]. Ostwald ripening is a dissolution-precipitation mechanism where the growth of larger particles occurs at the expense of smaller particles due to differences in relative surface energetics [ 41 ].…”

Section: Introductionmentioning

confidence: 99%

Elemental sulfur coarsening kinetics

García

Druschel

2014

Geochem Trans

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BackgroundElemental sulfur exists is a variety of forms in natural systems, from dissolved forms (noted as S8(diss) or in water as S8(aq)) to bulk elemental sulfur (most stable as α-S8). Elemental sulfur can form via several biotic and abiotic processes, many beginning with small sulfur oxide or polysulfidic sulfur molecules that coarsen into S8 rings that then coalesce into larger forms:Formation of elemental sulfur can be possible via two primary techniques to create an emulsion of liquid sulfur in water called sulfur sols that approximate some mechanisms of possible elemental sulfur formation in natural systems. These techniques produce hydrophobic (S8(Weimarn)) and hydrophilic (S8(polysulfide)) sols that exist as nanoparticle and colloidal suspensions. These sols begin as small sulfur oxide or polysulfidic sulfur molecules, or dissolved S8(aq) forms, but quickly become nanoparticulate and coarsen into micron sized particles via a combination of classical nucleation, aggregation processes, and/or Ostwald ripening.ResultsWe conducted a series of experiments to study the rate of elemental sulfur particle coarsening using dynamic light scattering (DLS) analysis under different physical and chemical conditions. Rates of nucleation and initial coarsening occur over seconds to minutes at rates too fast to measure by DLS, with subsequent coarsening of S8(nano) and S8(sol) being strongly temperature dependent, with rates up to 20 times faster at 75°C compared to 20°C. The addition of surfactants (utilizing ionic and nonionic surfactants as model compounds) results in a significant reduction of coarsening rates, in addition to known effects of these molecules on elemental sulfur solubility. DLS and cryo-SEM results suggest coarsening is largely a product of ripening processes rather than particle aggregation, especially at higher temperatures. Fitting of the coarsening rate data to established models for Ostwald ripening additionally support this as a primary mechanism of coarsening.ConclusionsElemental sulfur sols coarsen rapidly at elevated temperatures and experience significant effects on both solubility and particle coarsening kinetics due to interaction with surfactants. Growth of elemental sulfur nanoparticles and sols is largely governed by Ostwald ripening processes.

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Early stages of Ostwald ripening

Cited by 25 publications

References 19 publications

Three-dimensional resistivity and switching between correlated electronic states in 1T-TaS2

Three-dimensional resistivity and switching between correlated electronic states in 1T-TaS2

Reshaping, Intermixing, and Coarsening for Metallic Nanocrystals: Nonequilibrium Statistical Mechanical and Coarse-Grained Modeling

Elemental sulfur coarsening kinetics

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