THE STRUCTURE OF AMORPHOUS SOLIDS - A PERSPECTIVE VIEW

P. Gaskell

Structural data for a number of typical amorphous solids - elemental metals and semiconductors, amorphous alloys and oxide glasses - are surveyed and an attempt made to suggest the most appropriate models. Historically, random close-packed structures or random networks have been considered to be the most appropriate, especially for chemically simple amorphous solids - elemental metals and semiconductors, stoichiometric oxides. For more complex materials, there are a number of indications that random models are only tenable with some qualification - to allow chemical ordering, local and perhaps medium-range structural units, for instance. The particular example of alkali metasilicate glasses is discussed and it is shown that it is difficult to devise a suitably constrained random model which incorporates all the known experimental facts - defined coordination polyhedra for the alkali cations as well as the silicon atoms, a preference for SiO3-- units connected in chains, the measured density, as well as the experimental pair distribution functions. Questions are therefore raised : do random models represent the most general paradigm for the structure of amorphous materials, or are defective ordered models based on periodic or aperiodic packing more appropriate ? An attempt is made to suggest a strategy to answer such questions.

Domaines: Articles anciens

P. Gaskell. THE STRUCTURE OF AMORPHOUS SOLIDS - A PERSPECTIVE VIEW. Journal de Physique Colloques, 1985, 46 (C8), pp.C8-3-C8-20. ⟨10.1051/jphyscol:1985801⟩. ⟨jpa-00225131⟩