Disordered solids: universal behavior of structure, dynamics, and transport phenomena

Disordered materials (glasses and amorphous substances, melts, polymers, biological media, etc.) are an important class of objects. Despite the chaos usually associated with their structure, glasses and amorphous substances of various kinds (semiconducting, dielectric, metallic) possess a universal spatial scale length similar to 1 nm, an order parameter, which can be as important theoretically as the unit cell for crystals. The disorder in disordered substances is not absolute; the periodicity positions of atomic inherent in crystals is maintained within a few coordination spheres and is then somehow destroyed. The way in which the order breaks down makes it possible to distinguish the glasses from amorphous materials in terms of the form of the structural correlation function. The inhomogeneities in question are not exotic, unique formations or analogs of defects in crystals, but are the fragments out of which amorphous substances and glasses are entirely constructed. The spatial inhomogeneity of disordered substances having a characteristic scale length of similar to 1 nm leads to some universal characteristics in their vibrational properties, changes the relaxation mechanism for electronic excitation, and determines the specific features of charge transport. (C) 1999 American Institute of Physics. [S1063-7834(99)01205-8].