Materials for electrolyte: Fast-ion-conducting glasses

Abstract

Apart from crystalline materials, the second class of solid electrolytes is the family of amorphous conductors which in contrast more closely resemble liquid electrolytes than crystalline solids. It is easier to define an amorphous state by saying what it is not than by precisely specifying what it is. Amorphous materials are noncrystalline substances. They lack long-range periodic ordering of their constituent atoms. That is not to say that amorphous materials are completely disordered on the atomic scale. Local chemistry provides almost rigorous bond-length, and to a lesser extent, bond-angle constraints on the nearest-neighbor environment. For instance, unlike amorphous metals, amorphous semiconductors do not consist of close-packed atoms, but rather they contain covalently bonded atoms arranged in an open network with correlations in ordering up to the third- or fourth-nearest neighbors. The short-range order is directly responsible for observable semiconductor properties such as optical absorption edges and activated electrical conductivities.