Polycluster Concept of Amorphous Solids

Contrary to a periodic lattice, the symmetry of which is entirely characterized by its space group, the description of an amorphous structure faces the problem of no long-range order and of a local coordination that varies from site to site. The polycluster description of amorphous solids is a classification based on a set of Coordination Polyhedra (CP) for each atom determined by its nearest neighbors. Topologically equivalent polyhedra form classes and are referred to as 

Guntherodt, H. Beck (eds.) Glassy Metals I, Topics Appl. Phys., Vol. 46 (Springer, Berlin, Heidelberg 1981) 

The transformation of the crystalline into the glassy state by solid-state reactions is extensively reviewed in its theoretical and experimental aspects. First, we give some historical background and describe the thermodynamics of metastable phase formations, adding as well the kinetic requirements for the amorphization process. Then we discuss the different experimental routes into the amorphous state hydriding, thin diffusion couples, and other driven systems. In the discussion and the summary, we close the gap between the melting phenomena and the amorphization and provide a tentative outlook. 

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