Metastable liquids

Debenedetti P G 1996 Metastable Liquids (Prineeton, NJ Prineeton University Press)... 

The metastable liquid form boils at 44°C, the more stable solid alpha form melts at 62°C and has 25-30 J/g heat of fusion. This permits pressure generation when proceeding in either direction through the phase change. 

Debenedetti, P. G., Metastable Liquids Concepts and Principles, Princeton University Press Princeton, NJ, 1996... 

Supersaturation is the driving force for crystallization and is a prerequisite before a solid phase will appear in a saturated solution. Figure 1. shows the situation for a cooling crystallization. At point 1 the system is under saturated and the concentration of dissolved solute is below the solubility curve defined by Eq 3. As the system cools it becomes saturated at point 2 but remains as a metastable liquid phase until the metastable zone is crossed at point 3, where... 

Skripov, V. P. (1974). Metastable Liquids (translated from the Russian by R. Kondor). Wiley, New York. 

Solid polymer and gel polymer electrolytes could be viewed as the special variation of the solution-type electrolyte. In the former, the solvents are polar macromolecules that dissolve salts, while, in the latter, only a small portion of high polymer is employed as the mechanical matrix, which is either soaked with or swollen by essentially the same liquid electrolytes. One exception exists molten salt (ionic liquid) electrolytes where no solvent is present and the dissociation of opposite ions is solely achieved by the thermal disintegration of the salt lattice (melting). Polymer electrolyte will be reviewed in section 8 ( Novel Electrolyte Systems ), although lithium ion technology based on gel polymer electrolytes has in fact entered the market and accounted for 4% of lithium ion cells manufactured in 2000. On the other hand, ionic liquid electrolytes will be omitted, due to both the limited literature concerning this topic and the fact that the application of ionic liquid electrolytes in lithium ion devices remains dubious. Since most of the ionic liquid systems are still in a supercooled state at ambient temperature, it is unlikely that the metastable liquid state could be maintained in an actual electrochemical device, wherein electrode materials would serve as effective nucleation sites for crystallization. 

Berry, L. G., B. Mason, and R. V. Dietrich (1983). Mineralogy Concepts, Descriptions, Determinations, 2nd ed. W. H. Freeman, San Francisco. Blander, M., H. N. Planner, K. Keil, L. S. Nelson, and N. L. Richardson (1956). The origin of chondrales experimental investigation of metastable liquids in the system Mg2Si04Si02- Geochem. Cosmochem. Acta 40 889-896. 

The origin of the deep localized states in the mobility gap that control the dark decay has been attributed to structural native thermodynamic defects [12]. Thermal cycling experiments show that the response of the depletion time to temperature steps is retarded, as would be expected when the structure relaxes toward its metastable liquid-like equilibrium state. As the structure relaxes toward the equilibrium state, t(j decreases further until the structure has reached equilibrium. The only possible inference is that must be controlled by structure-related thermodynamic defects. The generation of such defects is, therefore, thermally activated. We should note that because the depletion discharge mechanism involves the thermal emission of carriers... 

Figure 19.22 Cross section of heterogeneous solid nucleus formed in a conical pit in the wall of a mold containing a metastable liquid.

We note that for aqueous solutions of some salts with ions of higher valence such as BaCl2 [73] or U02S04 [74] such a liquid-liquid immiscibility is indeed observed. Moreover, for some other salts such as MgS04 a metastable liquid-liquid immiscibility at elevated temperatures [76] seems to be suppressed by a retrograde salt solubility that rapidly decreases as the temperature is increased. 

In the second mechanism the topology of the pore network plays a role [394], During the desorption process, vaporization can occur only from pores that have access to the vapor phase, and not from pores that are surrounded by other liquid-filled pores. There is a pore blocking effect in which a metastable liquid phase is preserved below the condensation pressure until vaporization occurs in a neighboring pore. Therefore, the relative pressure at which vaporization occurs depends on the size of the pore, the connectivity of the network, and the state of neighboring pores. For a single ink bottle pore this is illustrated in Fig. 9.15. The adsorption process is dominated by the radius of the large inner cavity while the desorption process is limited by the smaller neck. 

In Sections III and IV, the principles of nucleation and growth were discussed separately. Now the crystallization process as a whole will be considered. In any practical application of crystallization, a stable solid phase must first be formed from the metastable liquid phase, and then additional molecules are deposited on the nucleus to form the macroscopic crystalline solid. Since nucleation and growth are taking place simultaneously, the theoretical principles discussed earlier are difficult to apply quantitatively to crystallization practice. Consequently, empirical expressions are still generally used in the design of equipment and prediction of its operation. 

In addition to the aforementioned conventional liquid organic solvents, two other types of molecular liquids have attracted much interest as supplementary or alternative media for synthesis and processing, namely supercritical fluids (sc-fluids) [209] and metastable liquids [210]. 

Water appears in various condensed forms 15 different crystalline ice structures are reported, as well as at least three amorphous (noncrystalline) ices and a similar number of metastable liquid water forms (14). This structural diversity has its origin in the elementary building blocks of water the hydrogen bonds and the tetrahedral arrangement of H-bonded neighbors [which is often called the Walrafen pentagon (15)]. Both building... 

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