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Highlights: [•] A minimum losses of 0.037dB/mm at 12μm are obtained in the Te-chalcogenide glass. [•] The absorption band of impurity Ga–O at 15–20μm was eliminated perfectly. [•] A cut-off based method to measure the bulk glass loss was proved effectively. [Copyright &y& Elsevier]

Abstract: The development of far infrared optical devices requires optical materials transmitting light far beyond 20μm. In this paper, two series of far-IR transmitting glasses including Ge–Te–Ga–Al and Ge–Te–Ga–AlCl3 were synthesized by melting–quenching method. Their thermal stability and IR transmitting property were investigated too. These glasses have wide infrared transmission region from 1.8 to 20μm, and the absorption peak of oxide in the 15–20μm region disappeared in the Fourier-transform infrared (FTIR) spectra when Al or AlCl3 was added into the Ge–Te–Ga system. The Ge–Te–Ga–Al glass samples show good thermal stability and high resistance to crystallization. Among these glasses, the (Ge0.15Te0.75Ga0.1)94Al6 glass has the highest glass transition temperature T g (196.3°C), and the Ge15Te75Ga6Al4 glass has the largest △T (126.2°C). In addition, the △T values of the Ge–Te–Ga–AlCl3 glass samples are all over 100°C and have small fluctuation, which are acceptable for practical application. [Copyright &y& Elsevier]

Abstract: 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 20at.%, 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 0.626eV in these glasses. These GeTe4.3–GaTe3–ZnI2 glasses show wide optical transmission and the infrared cut-off wavelengths are larger than 25μm, which implies that the Ge–Ga–Te–ZnI2 chalcogenide glasses possess the potential of far-IR optical window applications. [Copyright &y& Elsevier]