Structural evaluation on TeO₂–SeO₂–R₂O ternary glass system using Raman and IR

Structural evaluation on 70TeO₂–20SeO₂–10R₂O (R = potassium (K), sodium (Na) and lithium (Li)) ternary glass system has been studied using infrared (IR) and Raman techniques. Main building units of both glass formers (tellurium dioxide (TeO₂) and selenium dioxide (SeO₂)) play a vital role in the construction of amorphous network. According to the IR and Raman data, it is clear that the structural building units appearing in the glass system are selenium trioxide (SeO₃), lithium tetraoxide (LiO₄), potassium tetraoxide (KO₄), sodium oxide (NaO), tellurium trioxide (TeO₃) and tellurium tetraoxide (TeO₄). Adding alkali oxide to tellurium dioxide leads to a gradual reduction of the tellurium coordination from TeO₄ → TeO₃₊₁ → TeO₃; in addition to this, selenium dioxide also plays vital role in forming the glass structure. Mixing potassium, sodium and lithium to the selenium–tellurite glass system results in cleavage of Te–O–Te and Se–O–Se linkages by formation of TeO₃ ⁻ and SeO₃ ⁻ terminal groups. Among these, tellurium trioxide units are the dominant basic structural entities. Glass structural fragments are associated with the type of alkali oxide (potassium, sodium and lithium) and sterical hindrance of heavy alkali oxide produces distortions of the glassy network and reduces its rigidity.