Glass-formers

Glass former is sihca unless otherwise noted. See Table 1. 

Halide Glasses. Fluoride glasses are the most important of the haUde glasses. The only primary fluoride glass former is beryUium fluoride,... 

These are normally of pure platinum wound on a ceramic or glass former and encapsulated in a ceramic or glass shell, having an operating range of -250°C to +750°C,... 

NFS spectra of the molecular glass former ferrocene/dibutylphthalate (FC/DBP) recorded at 170 and 202 K are shown in Fig. 9.12a [31]. It is clear that the pattern of the dynamical beats changes drastically within this relatively narrow temperature range. The analysis of these and other NFS spectra between 100 and 200 K provides/factors, the temperature dependence of which is shown in Fig. 9.12b [31]. Up to about 150 K,/(T) follows the high-temperature approximation of the Debye model (straight line within the log scale in Fig. 9.12b), yielding a Debye tempera-ture 6x) = 41 K. For higher temperatures, a square-root term / v/(r, - T)/T,... 

Fig. 9.32 (a) Time evolution of the SRPAC signal (in log scale) for several temperatures obtained from the molecular glass former DBP doped with Fe-enriched ferrocene, (b) The relaxation rate X (in log scale) as a function of inverse temperature 1,000 obtained from analyzing the SRPAC... 

Silica, the universal glass former, generally makes up 60%-70% of the total mass of glass only in very few cases does the amount of silica exceed 70%. 

Figure 2 Sketch of typical temperature dependencies of the viscosity r of glass-forming systems. The viscosimetric Tg of a material is defined by the viscosity reaching 1013 Poise. Strong glass formers show an Arrhenius temperature dependence, whereas fragile glass formers follow reasonably well a Vogel-Fulcher (VF) law predicting a diverging viscosity at some temperature T0.

Polymers are very good glass formers, with a few notable exceptions. For some polymers, such as atactic polypropylene or random copolymers like... 

III. Test of the Adam-Gibbs Relaxation Model for Glass Formers Based on the Heat-Capacity Data of 1,3,5-Tri-a-Naphthylbenzene. 

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