BASIC STRUCTURE OF INFRARED GLASSES

A phenomenological theory, designated herein as the unified glass theory, is presented. The theory introduces the concept of order-disorder transitions and liquid-model transformation within a glass network and was found to be useful in elucidating and predicting structural behavior. The degree of order and the structural characteristics of a glass system were represented by three existing models of liquid structure Bernal, Stewart, and Frenkel. The unification of these three liquid models constitutes the basis of the proposed theory. Structure-sensitive flaws were utilized extensively in the study to facilitate the formulation of this network hypothesis. The unified glass theory has been applied successfully in categorizing various investigated vitreous systems, among them a nonoxide arsenic trisulfide glass, metaphosphate glasses, and barium silicate infrared systems. Microyield phenomena were critically examined, and the relationships between trace width and flaw number parameter are discussed. A correlation was suggested between the critical stress of defect formation and liquidus temperatures within a field of barium silicate infrared glasses.