Effect of iodine on physicochemical and optical properties of Ge20Te77-xSe3Ix (x = 0–10) glasses

Abstract

Thermodynamic modeling of the Ge-Te-I system is carried out. The dependences of the equilibrium concentrations of components in the condensed and vapor phases on temperature and iodine content are established. The compositional effect on the properties of Ge20Te77-xSe3Ix (x = 0–10) and Ge20Te72-ySeyI8 (y = 1, 3, 5) glasses is studied. In the glasses, with an increase in the iodine content, the glass transition temperature decreases, the stability against crystallization increases, and the short-wavelength transparency edge shifts towards shorter wavelengths. Selenium increases the stability of glasses against crystallization and limits transparency in the long-wavelength spectral range. The Ge20Te69Se3I8, Ge20Te67Se5I8, and Ge20Te67Se3I10 compositions are potentially suitable for fabricating optical fibers. The Ge20Te69Se3I8 glass sample with an oxygen impurity content chemically bonded with germanium of less than 50 ppb(wt) and low absorption in the 3–18 μm spectral range is prepared.