Heavy water supercooling

Crystallization of supercooled fat in topping powders may be studied by NMR afterreconstitution in heavy water. Below room temperature spontaneous fat crystallization takes place under isothermal conditions in the presence of effective emulsifier (PGMS) but not with ineffective emulsifiers or without emulsifiers (Figure 4). 

Keywords metastable state, water, heavy water, superheating, supercooling, nucleation rate, explosive boiling up, density, sound velocity... 

Experimental results obtained in isothermal conditions for light and heavy water are presented in Fig. 5. For light water they cover a range of nucleation rates of 5 orders in the interval of supercoolings from 33.9 to 37.8 K. In this interval the nucleation rate increased 10 times when the temperature decreased by 0.8 K. The effective value of the surface tension calculated from experimental data is ct, = 28.7 mN/m, and the value of the preexponential... 

Fig. 5 gives temperature dependences of the stationary nucleation rate for supercooled and heavy water under crystallization of amorphous layers (dots on the low-temperature branch of the dome of J T)). 

Water in the supercooled state has been studied less thoroughly than in the superheated one. Experimental data mainly refer to pressures close to atmospheric. Ice exists in different crystalline forms, and the water phase diagram has an elaborate form if one does not restrict oneself to the region of low pressures p < 200 MPa). The pol5miorphism of ice may manifest itself at a low pressure too. It has been found that during crystallization of amorphous layers of light and heavy water there forms a mixture of hexagonal and cubic ice. 

The cell in Fig. 4.5 represents a fixed value of chemical drive just as the original meter and the original kilogram in Paris represent fixed length and mass values. This example shows the solidification of supercooled heavy water (freezing point 276.97 K),... 

It is interesting, however, to comment on the level of supercooling possible for heavy water in Vycor. According to Ref. 48, for partially... 

E. Lang, H.-D. Luedemann, Rressure and temperature dependence of the longitudinal deuterium relaxation times in supercooled heavy water to 300 MRa and 188 K, Ber. Bunsenges. Rhys. Chem. 84(1980)462-470. 

Yokoyama, E. et al. (2011) Measurements of growth rates of an ice crystal from supercooled heavy water under microgravity conditions basal face growth rate and tip velocity of a dendrite. J. Phys. Chem., B115, 8739-8745. 

Rasmussen, D.H., MacKenzie, A.P., Angell, C.A. and Tucker, J.C. (1973) Anomalous heat capacities of supercooled water and heavy wdXer,Science 181,342. 

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