BASIC STRUCTURE OF INFRARED GLASSES

Abstract : This report describes initial results in a program directed toward a better understanding of the basic structure of infrared glasses. In general, the experimental methods involved detailed studies of changes in the internal bonding energy of the glass. Structure-sensitive surface flaws are utilized as one means of quantitatively determining these energy changes. An indenter device used to produce these flaws under known loading conditions is described; and, with working equations, it is possible to determine the critical stress of flaw formation. The data obtained in the initial phases of this study strongly suggest that the approach of relating characteristics of the infrared spectra of glass systems to variations in structure-related mechanical properties such as the characteristics of the surface flaws provides considerable information regarding variations in the internal bonding energies. Variations in the flaw parameters and infrared transmission characteristics were found to agree with theoretical predictions of internal energy changes based on the manner in which a specific ion entered the network of the glass, that is, as a lattice modifier or as an interstitial or network former. Results are presented for soda-lime-silica as well as for a calcium aluminate structure. (Author)