Modeling and experimental determination of physical properties of GexGaySe1-x-y chalcogenide glasses II: Optical and thermal properties

Abstract

This study systematically analyzed the correlation between topological structure and chemical ordering on the optical and thermal properties of synthesized material in the glass forming region of the GexGaySe1-x-y ternary. A series of ten compositions from 5 to 30 mol% Ge and 5 to 15 mol% Ga were examined within the ternary, showing broadband infrared properties with transmission from 1 to 25 μm. Topological constraint theory applied to compositions examined exhibited sharp inflection at the average coordination number of <r> = 2.67 defined as the chemical threshold where the glass network consists of tetrahedral Ge(Ga)Se2 units. These observations indicate that thermal and optical properties in these chalcogenide glasses are highly sensitive to the chemical ratio of homopolar versus heteropolar bonds, Ge to Ga ratio, as well as the dimensionality of the topological structure. Glass transition and crystallization temperature values compare well with previous literature on similar GeXSe systems. This is a comprehensive study that systematically examined thermal conductivity, heat capacity, absorption coefficient, and refractive index within the GexGaySe1-x-y system, correlating these properties with structural network calculations. The presented methodology and findings will enable the compositional design of materials for infrared systems using GexGaySe1-x-y glasses with broadband transmission.