Crystal growth eutectic

Fig. 1. 28.1. DTA measurement of a 10% sucrose-10% NaCI solution during slow rewarming after quick (200 °C/min) freezing. 1, Glass transition at = 93 °C 2, crystal growth (exothermic) at -65 °C 3, significant exothermic event, crystallization of NaCI at =44 °C 4, eutectic melting at =22 °C ...

It is instructive to consider the free-energy hierarchy and the metastable phase equilibria when crystallization of an amorphous material is discussed. Koster and Herold [56] discussed these aspects of crystallization and showed that crystallization reactions of amorphous alloys can be classified into the following three types polymorphic, primary and eutectic crystallization reactions. Among these three types, the slowest crystal growth process is expected for primary crystallization and thus, primary crystallization is ideal for tailoring fine microstructures upon decomposition of amorphous alloys. 

An awareness of crystal packing characteristics and polymorphism helps one to understand incompatibility problems of different fats. Crystal formation has specific demands, and individual crystals in mixed systems each consists of only one species ofTAG. However, surfactants and other molecules can act as impurities and interrupt crystal growth. Different TAG are considered compatible when they co-crystallize as separate crystals under the same conditions without the formation of a eutectic. 

CRYSTAL GROWTH OF ICE-I/HYDRATE EUTECTIC BINARY SOLUTIONS... 

The onset of crystallization within the test tubes occurred wherever a nucleation site was available, typically on the inner wall or on the thermocouple rod. Large, feathery crystals were often observed growing into the sample. To control growth and circumvent the thermodynamic barrier to nucleation, we in some instances used a small bit of seed material with the same bulk composition as the solution. The density of the eutectic solid in all instances is less than that of the liquid solution. Thus, when the seed was deployed, it floated on the surface and crystal growth continued downward with a nearly planar solid-liquid interface. 

Borodin, V.A., Starostin, M.Y., and Yalovets, T.N., Structure and related mechanical properties of shaped eutectic Al203-Zr2(Y20j) composites, J. Crystal Growth 194 (1990) 148-153. 

Lee, J.H. et al.. Microstructure of Al203-Zr02 eutectic fibers grown by the miao-puUing down method, J. Crystal Growth 222 (2002) 791-796. 

Eutectic forming mixtures provide a theoretical opportunity to achieve one component by crystallization that has 100% purity. This is of course only possible if, on the one hand, the crystal growth rates are so extremely slow that perfect crystals are created and, on the other hand, the necessary solid-liquid separation after the growth process is also perfect. 

Gupta, R.K., Singh, R.A., 2004. Thermochemical and microstructural studies on binary organic eutectics and complexes. Journal of Crystal Growth 267,340-347. 

Singh, N.B., Rai, U.S., Singh, O.P., 1985. Chemistry of eutectic and monotectic phenanthrene-succinonitrile system. Journal of Crystal Growth 71,353-360. 

Abbreviations e, eutectic melting, p, peritectic decomposition, pe, peritectic-eutectic reaction, av, availaMe for crystal growth, ltd, limited possibility for crystal growth, none, not recommended for crystal growth. 

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