Ostwald ripening, description

This growth mechanism, known as Ostwald ripening, provides a good description of the growth behavior of a wide range of nanoparticles [71, 76, 135-137]. A thorough analysis of the fundamental equations (44 and 45) leads to a general expression of the type [138-140]... 

Examples of atomistic models addressing PEMFC materials s stability and aging, a) DFT modeling of surface oxide formation b) atomistic description of nanoparticle (Ostwald) ripening c) calculation of surface and bulk composition of alloyed catalyst d) change of potential as function of alloy composition. 

Several breakdown processes may occur on storage depending on (i) Particle size distribution and density difference between the droplets and the medium, (ii) Magnitude of the attractive versus repulsive forces which determine flocculation, (iii) Solubility of the disperse droplets and the particle size distribution which determine Ostwald ripening, (iv) Stability of the liquid film between the droplets that determines coalescence. (v) Phase inversion. The various breakdown processes are illustrated in the Fig. 3.32. This is followed by a description of each of the breakdown processes and methods that can be applied to prevent such instability. 

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