Chalcogenide glasses transmitting in the infrared between 1 and 20 μ — a state of the art review

Abstract

The chalcogenide glasses offer a new range of infrared transmitting materials to the designer and this review attempts to bring together the currently available data on these glasses. Information is presented on glass preparation, composition, softening temperature, thermal expansion, viscosity, chemical durability, mechanical properties, electrical properties, infrared transmission, refractive index and absorption coefficient, with particular emphasis on infrared transmission. Recent work has shown that impurity absorption bands have limited the infrared transmission of chalcogenide glasses. However, these absorption bands can be removed so that the useful range of transmission is extended. Thus, sulphide glasses transmit between 0.6 and 11.5 μ, selenide glasses transmit between 1 and 15 μ and telluride glasses transmit between 2 and 20 μ. The maximum softening temperatures which have been achieved are 500°C in sulphide systems, 450°C in selenide systems and 466°C in telluride systems.