Nucleation critical particle size

For large sizes the particles are multi-domain becoming more bulk-like with increasing size. The mechanism of magnetization reversal is domain wall nucleation and motion for the multi-domain case [1], As the particle size is reduced the increase of energy due to domain wall formation dominates over the decrease in energy attributed to the formation of domains. Thus, below a critical particle size domain walls will no longer... 

On physical grounds, loa = 0 because there is no toss of particles by growth from the upper end of the distribution. The term /,/ is the particle current (lowing into the lower end of the spectrum. When homogeneous niicleation takes place, this term is important. For vj = v, the critical particle size, /,j, is the particle current of homogeneous nucleation theory. Hence the dynamic equation for the number concentration is... 

The term (3 /g v dv)/dt represents the accumulation of material in the cluster size range below the critical particle size range u. In homogeneous nucleation theoiy (Chapter 10), this term vanishes there is a steady state for this portion of the distribution in which material is removed as fast as it is supplied. (This is actually true only as a quasi-steady approximation.) The second term on the right-hand side of (11.18) can be written as follows ... 

In Figure 13 the relation between the intrinsic coercivity and the particle diameter dis given. The figure is based on a described model (35). The maximum is found around the critical particle diameter. In general the particle diameter and size is not very well defined. For the multidomain particles (d > ) the is smaller than the intrinsic anisotropy field of the particle. Nucleation effects cause a decrease in as the increases. This behavior is... 

A reduction in the magma density will generally increase nucleation and decrease the particle size. This technique has the disadvantage that crystal formation on the equipment surfaces increases because lower shiny densities create higher levels of supersaturation within the equipment, particularly at the critical boiling surface in a vaporization-type ciystaUizer. 

A subcritical aggregate having fewer subunit components than a nucleus. When this term is applied in the kinetics of precipitation, n refers to the number of subunits in a particle and n defines the number of subunits in a particle of critical size. This definition avoids confusion by distinguishing between subcritical (n < n subunits), critical (n = n subunits), and supercritical (n > n subunits) particle sizes. If a nucleus is defined as containing n n subunits, then an embryo contains n n subunits. Note that in this treatment, we are not using a phase-transition description to describe nucleation, and we are focusing on the smallest step in the process that leads to further aggregation. 

It appears that both compatibilization and the nanostructure formation at the interface play a key role for nucleation. The supposed heterogeneous nucleation activity will therefore be discussed in more detail. Heterogeneous nucleation in general is strongly affected by the particle size and the interfacial properties [79, 80], As the particle size of the PPE phase is well above the critical radius of nucleation of several nanometers [80], the interface demands closer examination. 

The droplet current / calculated by nucleation models represents a limit of initial new phase production. The initiation of condensed phase takes place rapidly once a critical supersaturation is achieved in a vapor. The phase change occurs in seconds or less, normally limited only by vapor diffusion to the surface. In many circumstances, we are concerned with the evolution of the particle size distribution well after the formation of new particles or the addition of new condensate to nuclei. When the growth or evaporation of particles is limited by vapor diffusion or molecular transport, the growth law is expressed in terms of vapor flux equation, given by Maxwell s theory, or... 

The surface activity of these compounds was not studied in detail. As mentioned in the Experimental Section, all were about equivalent in nucleating particles during emulsion polymerization. The resulting latexes when dialyzed to remove excess salt were stable against settling even at 10% solids over many months. Data on samples where both latex particle size and critical micelle concentration were measured is shown in Table II. 

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