Oswald ripening

Nyvlt et al. (1985) showed that for the case of a pure crystal of species A, the relationship between the bnlk solnbility of A in solution Caoo and the solubility of a small particle of radius f in the same solution Caj is given by 

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Figure 10.11 A well-ordered 2D AuS phase develops during annealing to 450 K. (A) The structure exhibits a very complex LEED pattern, which can be explained by an incommensurate structure with a nearly quadratic unit cell. (B) STM reveals the formation of large vacancy islands by Oswald ripening which cover about 50% of the surface, thus indicating the incorporation of 0.5 ML of Au atoms into the 2D AuS phase. The 2D AuS phase exhibits a quasi-rectangular structure (inset) and uniformly covers both vacancy islands and terrace areas. (Reproduced from Ref. 37).

In this chapter, we review some results in the field of emulsion metastability, emphasizing the destruction of concentrated emulsions (droplet volume fraction

70%) through coalescence. The review concerning Oswald ripening (Section 5.2) is more concise, as this mechanism is fairly well understood and has been extensively documented in the literature. So far, the destruction of concentrated emulsions through coalescence is much less understood and has motivated many recent studies and developments that we summarize (Sections 5.3 to 5.6). 

In some cases, due to coalescence mechanisms (Oswald ripening), bimodal particle-size distributions are observed. 

Physical form and particle size growth (Oswald Ripening) may... 

In this chapter, a summary of the methods that can be applied to assess the structure of the solid/Uquid interface will first be provided, followed by details of assessing sedimentation, flocculation, and Ostwald ripening. In the latter cases (flocculation and Oswald ripening), information is needed on the particle size distribution, and several techniques are available to obtain this from diluted systems. It is essential to dilute the concentrated suspension with its own dispersion medium in order not to affect the state of the dispersion during examination. The dispersion medium can be obtained by centrifuging the suspension, when the supernatant liquid will be produced at the top of the centrifuge tube in the case... 

It is also advantageous to use special protective colloids, which influence the main two effects of droplet enlargement Oswald ripening and coalescence. The main reactions of the splitting off of formaldehyde, which give rise to residual formaldehyde in the capsule dispersions and MF microcapsule systems used, are shown in Figure 60.10. 

A confirmed the presence of unintercalated Na -montmorillonite. Nevertheless, surface area measurements and subsequent neutron scattering studies [5] of the silica sol - clay products were indicative of the formation of composite structures in which the sol particles bind to the basal surfaces of the clay aggregates and become stabilized against particle growth through Oswald ripening. 

Essentially, the stability of the foam depends on the stability of the individual film, with champagne foams being a classic example of an unstable foam (Figure 2.2(a)). In this case, the lifetime is controlled by the drainage (hydrodynamics), but also gas diffusion and Oswald ripening probably play a role in destabilizing the system. 

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