Structural evolution study of additions of Sb₂S₃ and CdS into GeS₂ chalcogenide glass by Raman spectroscopy

The structures of pseudo-binary GeS₂-Sb₂S₃, GeS₂-CdS, Sb₂S₃-CdS, and pseudo-ternary GeS₂-Sb₂S₃-CdS chalcogenide systems are systematically investigated by Raman spectroscopy. It is shown that a small number ofS₃Ge-GeS₃ structural units (SUs) and -S-S-/S₈ groups exist simultaneously in GeS₂ glass which has a three-dimensional continuous network backbone consisting of cross-linked corner-sharing and edge-sharingGeS₄ tetrahedra. When Sb₂S₃ is added into GeS₂ glass, the network backbone becomes interconnectedGeS₄ tetrahedra andSbS₃ pyramids. Moreover, Ge atoms inS₃Ge-GeS₃ SUs tend to capture S atoms from Sb₂S₃, leading to the formation ofS₂Sb-SbS₂ SUs. When CdS is added into GeS₂ glass,Cd₄GeS₆ polyhedra are formed, resulting in a strong crystallization tendency. In addition, Ge atoms inS₃Ge-GeS₃ SUs tend to capture S atoms from CdS, resulting in the dissolution of Ge-Ge bond. Co-melting of Sb₂S₃ or CdS with GeS₂ reduces the viscosity of the melt and improves the homogeneity of the glass. The GeS₂ glass can only dissolve up to 10-mol% CdS without crystallization. In comparison, GeS₂-Sb₂S₃ glasses can dissolve up to 20-mol% CdS, implying that Sb₂S₃ could delay the construction ofCd₄GeS₆ polyhedron and increase the dissolving amount of CdS in the glass.