Glass Formation General Consideration

The main purpose of this section is to give an account of general peculiarities of the microscopic scenarios of the supercooled liquid solidification and to show that formation of the polycluster glasses is a commonplace case. A more detailed consideration of the supercooled liquid structure, its thermodynamics and solidification kinetics is given in Sect. 6.10. 

Crystalline as well as noncrystalline solid nuclei may form in the melt. The term noncrystalline means that the mutual location of atoms in the nucleus possesses no symmetry compatible with the translational invariance (e.g., it has 

1 The systems with broken ergodicity and the methods of their description are considered in the review article [6.11]. 

In the formulae for the nucleation rates, the frequencies of atom attachment to nuclei come into play as well although the exponents pointed out above are 

If the behavior of the A Gc and AGcl with T- Tt becomes as shown in Fig. 6.1b, then the crystallization of the supercooled melt is generally hampered and has small probability because AGC(NZ) ACcl(N ) thus, at first, a noncrystalline solid forms by nucleation and growing of noncrystalline precipitates. 

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