Glass formation and properties of Ge–Ga–Te–ZnI2 far infrared chalcohalide glasses

In order to develop novel far infrared window material, a series of Ge–Ga–Te–ZnI2 chalcohalide glasses were prepared by traditional melt-quenching method and their glass-forming region was determined also. Here, some measurements including X-ray diffraction (XRD), differential thermal analysis (DTA), UV–Vis–NIR absorption spectrum, and infrared optical transmission spectra were carried out. The allowed indirect transition optical band gap was calculated according to the classical Tauc equation. The results show that with the addition of ZnI2, the glass-forming ability and thermal stability are improved gradually. With the contents of ZnI2 increased from 5 to 20 at.%, continued blue-shifting occurs in the cutting-off absorption edge of short-wavelength and the values of indirect optical band gaps were observed with ranges from 0.596 to 0.626 eV in these glasses. These GeTe4.3–GaTe3–ZnI2 glasses show wide optical transmission and the infrared cut-off wavelengths are larger than 25 μm, which implies that the Ge–Ga–Te–ZnI2 chalcogenide glasses possess the potential of far-IR optical window applications.