Study On Composition, Structure And Properties Of GeS₂-Ga₂S₃-AgCl Chalcohalide Glasses

Content: Utilizing the techniques such as X-ray diffraction (XRD), Raman spectra, comprehensive thermal analysis, UV-Vis-IR spectra, femtosecond time-resolved optical Kerr gate technique (OKE), and Maker fringe technique etc., structure and properties has been studied systematically of the GeS₂-Ga₂S₃-AgCl pseudo-ternary system. The obtained summaries are as follows:The glass-forming region of the pseudo-ternary GeS₂-Ga₂S₃-AgCl system is ascertained. The amount of dissolved Ga₂S₃ and AgCl are up to 30mol% and 65mol%, respectively.Raman spectra of samples within GeS₂-Ga₂S₃-AgCl system were reported for the first time. Furthermore, assignments and evolution of spectra on every series had been elucidated reasonably according to the addition of glass modifier AgCl.The microstructure of pseudo-ternary GeS₂-Ga₂S₃-AgCl system is shown as follows: [Ge(Ga)S_4-xCl_x] mixed tetrahedral s.u. and [Cl_xS_3-xGe(Ga)-Ge(Ga)S_3-xCl_x] ethane-like s.u. form the basic glass network via bridging sulfur bonds. With the addition of AgCl, the ethane-like s.u. gradually transform into tetrahedral s.u.. Ag⁺ions can be dissolved into the glass network as charge compensators.The glasses in this pseudo-ternary system have relatively high glass transition temperatures, good thermal stabilities, broad transparencies (0.44-10.5μm) and large refractive indices. With the addition of AgCl, the ultraviolet cut-off edge (λ_vis) shifts toward the long wavelength and the glass transition temperature (T_g) also decreases gradually.Utilizing femtosecond time-resolved OKE technique, the third-order nonlinear susceptibility,χ⁽³⁾ is estimated to be as large as 5.26×10^-13 esu at 820nm of A2 glass (80GeS₂-10Ga₂S₃-10AgCl). The response time of glasses is subpicosecond, which is dominantly assigned to the ultrafast distortion of the electron cloud. The compositional and structural dependence of the value ofχ⁽³⁾ was also discussed in detail. In addition, using Maker fringe technique, second-harmonic generation (SHG) was observed in the representative A2 (80GeS₂-10Ga₂S₃-10AgCl) chalcohalide glass poled by electron beam (25 kV, 25 nA, 15 min), and the second-order optical nonlinear susceptibility is as large as 6.1 pm/V. No any microstructure transformation was detected in glass after irradiation from the Raman spectra. All the properties summarized above indicate that these GeS₂-Ga₂S₃-AgCl chalcohalide glasses can be applied potentially in optoelectronic fields.