Novel Ge–Ga–Te–CsBr glass system with ultrahigh resolvability of halide

• Ge–Ga–Te host glass can dissolve the content of CsBr as much as 85 at.%.
• The ΔT values of (Ge15Ga10Te75)65 (CsBr)35 glass sample can reach to 119 °C.
• The infrared cut-off wavelength could reach up to 25 μm.
• The absorption peaks in the infrared transmission spectra disappeared through a purifying method.

CO2 molecule, one of the main molecules to create new life, should be probed accurately to detect the existence of life in exoplanets. The primary signature of CO2 molecule is approximately 15 μm, and traditional S- and Se-based glass fibers are unsuitable. Thus, Te-based glass is the only ideal candidate glass for far-infrared detection. In this study, a new kind of Te-based chalcohalide glass system was discovered with relatively stable and large optical band gap. A traditional melt-quenching method was adopted to prepare a series of (Ge15Ga10Te75)100−x (CsBr)x chalcogenide glass samples. Experiment results indicate that the glass-forming ability and thermal properties of glass samples were improved when CsBr was added in the host of Ge–Ga–Te glass. Ge–Ga–Te glass could remarkably dissolve CsBr content as much as 85 at.%, which is the highest halide content in all reports for Te-based chalcohalide glasses. Moreover, ΔT values of these glass samples were all above 100 °C. The glass sample (Ge15Ga10Te75)65 (CsBr)35 with ΔT of 119 °C was the largest, which was 7 °C larger than that of Ge15Ga10Te75 host glass. The infrared transmission spectra of these glasses show that the far-infrared cut-off wavelengths of (Ge15Ga10Te75)100−x (CsBr)x chalcogenide glasses were all beyond 25 μm. In conclusion, (Ge15Ga10Te75)100−x (CsBr)x chalcogenide glasses are potential materials for far-infrared optical application.

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