Low-frequency Raman scattering in alkali tellurite glasses

Raman scattering has been employed to study the alkali-cation size dependence and the polarization characteristics of the low-frequency modes for the glass-forming tellurite mixtures, 0⋅1M2O-0⋅9TeO2 (M = Na, K, Rb and Cs). The analysis has shown that the Raman coupling coefficient alters by varying the type of the alkali cation. The addition of alkali modifier in the tellurite network leads to the conversion of the TeO4 units to TeO3 units with a varying number of non-bridging oxygen atoms. Emphasis has also been given to the low- frequency modes and particular points related to the low-frequency Raman phenomenology are discussed in view of the experimental findings.