Formation glasses

Consider the crystallization of a melt with a freezing point T, . At the free-energy change per mole associated with the solid-to-liquid 

The energy changes that have to be considered during homogeneous nucleation include 

If one assumes spherical nuclei with a solid-liquid interfacial energy between the growing nucleus and the melt 7 1 and radius r, and if one ignores 

Strain effects, the energy changes that accompany their formation are 

Equation (9.4) represents the local increase in free energy due to the formation of a nucleus, and not the total free energy of the system. The latter must include the configurational entropy of mixing of n nuclei in the liquid. When that term is included, the total free energy of the system decreases as it must (see App. 9A). 

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Fig. 11. Index of refraction vs dispersion and optical classification of glasses. The shaded area indicates the region of glass formation. BaF = barium flint BaK = barium crown BaLF = light barium flint BaSF = heavy barium flint BK = borosilicate crown F = flint FK = fluorcrown K = crown ...

Dichroma.te(VI) Glasses. Alkali dichromate(VI) glasses exist in systems such as Li2Cr20y—Na2Cr20y. The glass-transition temperatures of the dichromates are very low, about 0°C. The addition of chlorides or nitrates aids in glass formation. 

Fig. 16.5. Glass formation. A 3-co-ordinoted crystalline network is shown at (a). But the bonding requirements are still satisfied if o random (or glassy) network forms, as shown at (b). The network is broken up by adding network modifiers, like NojO, which interrupt the network as shown at ( ).

G. I. Menon, R. Pandit. Glass formation in a lattice model for living polymers. Phys Rev Lett 75 4638-4641, 1995. 

G. B. McKenna. Glass formation and glassy behavior. In C. Booth, ed. Comprehensive Polymer Science. New York Pergamon, 2 311-362, 1989. 

The thermal behavior of many ionic liquids is relatively complex. For a typical IL, cooling from the liquid state causes glass formation at low temperatures solidifica-... 

BULK METALLIC GLASS FORMATION IN THE Pd-Ni-P and Pd-Cu-P ALLOY SYSTEMS... 

Figure 2. Bulk glass formation range in Pd-Ni-P system. Filled eireles denote the formation of amorphous phase, open eireles denote the formation of erystalline phases.

Utilizing this description of silicate glass formation, we suggest models to explain the incorporation of 4+ and 6+ actinide ions in sodium disilicate glass. During cooldown,... 

Typically, in solution-phase film deposition, a precursor coating is applied to a surface and heated, whereupon the elimination of solvent leads to localized crystallization and separation of solid particles. To prevent these processes, metal-organic precursors can be commonly employed for sol-gel deposition (see Chapter 2), wherein the organic ligands essentially act as vehicles to promote glass formation. Ultimately, embedded organic ligands... 

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