Non-crystalline solids: Glasses and amorphous solids

Zachariasen's concept of glass formation has seen extended to rationalize the relative ease of different compositions for formation of non-crystalline solids. It is shown that non-crystalline solids can be divided in to two thermodynamically distinct classes: glasses and amorphous solids. Further, it is argued that they behave differently upon heating. Based on Zachariasen's notion of glass as a topologically disordered network with short range order equivalent to that in the corresponding crystal, quantitative structure-based definitions are proposed for glasses and amorphous solids. In addition, a previous formalism based on degrees of freedom in topologically disordered networks has been extended to examine the relative abilities of compositions to form non-crystalline solids.