Vitrification as Avoidance of Crystallisation

Apart from the ice polymorphs, other types of solid but non-crystalline water exist, and they apparently form the most abundant state of H2O in the universe, where they are found adsorbed onto interstellar dust particles that eventually form comet tails. Amorphous, glassy water is mentioned here only for the sake of completeness, because its properties 

According to some researchers, the two states are in fact two distinct phases, with real coexistence boundaries. If this claim can ever be verified, then it follows that there should exist a second critical point for water, akin to the critical point at 374°C, where the liquid and gas phases coalesce. It may, however, be impossible to confirm the existence of such a point by experiment, because it would lie well below Thom where freezing cannot be avoided. 

While amorphous water as such may not figure in freeze-drying technology, the opposite is true for many of the other components that make up the finished pharmaceutical preparation. In fact, the realisation of the importance of amorphism in pharmaceutical product development has led to the birth of a new scientific discipline pharmaceutical materials science. Successful freeze-drying is firmly based on the same 

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