Kinetic crystallization growth theories

He started to work at the Chemical Faculty of Sofia University where he became a professor and the head of the Department of Physical Chemistry, in 1947. Kaishev founded the Institute of Physical Chemistry of the Bulgarian Academy of Sciences in 1958, and helped to establish the Central Laboratory of Electrochemical Power Sources [i]. Kaishev started to collaborate with - Stran-ski in Berlin in 1931 [iii] and became his assistant in Sofia in 1933. They laid the fundamentals of the crystal growth theory. They proposed the first kinetic theory of the two-dimensional nucleation and growth. The spiral type growth during electrocrystallization was first observed by Kaishev on silver [iii]. On the history of the creation of the molecular-kinetic theory of crystal growth see [iv]. 

In the previous section, we reviewed a number of different crystal growth theories. These provide a theoretical basis for the correlation of experimental crystal growth data and the determination of kinetic parameters from the data to be used in models of... 

In our discussions of crystal growth theory and kinetics, we have assumed that the crystal growth rate is not a function of crystal size. While a good first assumption, this is not always true. As we saw in our discussion of Ostwald ripening, there is a difference in solubility between very small particles and larger particles. This differential solubility will result in a difference in supersaturation as a function of particle size. The smaller particles will be at a lower supersatura-... 

Having discussed some equilibrium properties of a crystal, we now outline and contrast the bases of the growth theories which will be dealt with in more detail later. The theories may be broadly split into two categories equilibrium and kinetic. The former [36-42] explain some features of the lamellar thickness, however the intrinsic folding habit is not accounted for. Therefore, at best, the theory must be considered to be incomplete, and today is usually completely ignored. We give a brief summary of the approach and refer the interested reader to the original articles. The kinetic theories will be the topic of the remainder of the review. 

It has been reported that the overall rate of crystallization of pure PHB is relatively low compared to that of common synthetic polymers, showing a maximum in the temperature range of 55-60°C [23]. The spherulite growth rate kinetics have been evaluated [59] in terms of the theory by Hoffmann et al. [63], At about 90 °C, the spherulite growth rate displayed a maximum, which is not excessively low compared to that of common synthetic polymers. Therefore it was stated that the low overall crystallization rate of PHB centers on the nuclea-tion process rather than the subsequent crystal growth. Indeed, it has been shown that PHB has an exceptionally low level of heterogeneous nuclei [18]. 

F. C. Frank, On the kinetic theory of crystal growth and dissolution process, in Growth and Perfection ofGrystals, eds. R. H. Doremus, B. W. Roberts, and V. Turnbull, New York, John Wiley Sons, 1958... 

One of the most controversial topics in the recent literature, with regard to partition coefficients in carbonates, has been the effect of precipitation rates on values of the partition coefficients. The fact that partition coefficients can be substantially influenced by crystal growth rates has been well established for years in the chemical literature, and interesting models have been produced to explain experimental observations (e.g., for a simple summary see Ohara and Reid, 1973). The two basic modes of control postulated involve mass transport properties and surface reaction kinetics. Without getting into detailed theory, it is perhaps sufficient to point out that kinetic influences can cause both increases and decreases in partition coefficients. At high rates of precipitation, there is even a chance for the physical process of occlusion of adsorbates to occur. In summary, there is no reason to expect that partition coefficients in calcite should not be precipitation rate dependent. Two major questions are (1) how sensitive to reaction rate are the partition coefficients of interest and (2) will this variation of partition coefficients with rate be of significance to important natural processes Unless the first question is acceptably answered, it will obviously be difficult to deal with the second question. 

In all kinetic theories of polymer crystallization [8] the crystal growth rate G... 

The morphology of a microcrystal depends in a complex way on the thermodynamics and kinetics that determine the stabilities of the faces and their growth. Currently, an exhaustive theory of crystal growth in different atmospheres is not available nevertheless, a reasonable prediction of surface morphology based on the bulk crystalline structure of the solid is possible in many cases. 

This chapter is concerned with the growth of crystals from aqueous systems. The approach is to present the fundamental concepts which are vital to the understanding of growth processes. This is followed by a discussion of the most important techniques available to the experimentalist and how the growth may be interpreted using current theories of crystal growth. Finally, the effects of impurities on the growth kinetics are examined. 

On closer scrutiny the crystal growth data for PEO fractions deviated somewhat from those expected from secondary nucleation theory there were departures from linearity of Gvs AT near the Tcm transition temperatures,185 188 and the value of a derived from the kinetics was unrealistically low.187... 

Mutaftschiev, B. Nucleation theory. In Handbook of Crystal Growth la Thermodynamics and Kinetics-, Hurle, D.T.J., Ed. North-Holland Amsterdam, 1993 Chapter 4, 307-475. 

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