Structural model of the Ge-Sn-Se glasses, and its evolution with incorporation of Sn.

Qiao, B., Chen, F*., et al. Journal of the American Ceramic Society 100(1), 108-114 (2017).

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The flexible form of chalcogenide glasses (ChGs), such as e.g. bulk (fiber), thin film, or even solution leads to great potentials of GhGs in realization of infrared photonic devices based on third-order nonlinearity (TONL), such as all-optical switching, supercontinuum generation, wavelength conversion et al.

Recently, Beijing Qiao and Feifei Chen et al. present a systematic investigation of the optical and structural properties of chalcogenide glasses in Ge–Sn–Se ternary system. A threshold behavior of optical properties, namely, existence of transitional composition of the Ge-Sn-Se glasses, with progressive replacement of Se by Sn has been found. Calculation of mean coordination number indicates that the transition-like feature of optical properties is associated with the evolution of chemical ordering of the Ge–Sn–Se network. Analysis of Raman spectra of the glasses explains that interaction between Se–Se chain bonds, Sn(Se_1/2)₄ tetrahedra, and Sn–Sn homopolar bonds is the origination of such optical phenomenon.

The variation in the optical bandgap energy (E_g) with the mean coordinate number of the two Ge-Sn-Se glass sets.

Paper link: https://onlinelibrary.wiley.com/doi/abs/10.1111/jace.14477