Molecular Structure of Tellurium-Based Optical Glasses and Liquids by Spectroscopy and Calorimetry

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The molecular structure of two new classes of tellurium-based optical glasses will be investigated using Mossbauer spectrosopy, Raman spectroscopy, and calorimetry. The alkaline and alkaline- earth tellurates will be alloyed with germanium to modify the glass transition temperatures of these amorphous materials. The fragility of corresponding glassy melts will be established by viscosity-and enthalpy-activation energies and thermal expansion measurements. The results will be correlated with aspects of glass molecular structure deducted from spectroscopy. Of particular interest is the average coordination around the probe ions (iodine and tellurium). On a basic level, the present glasses provide convenient systems to explore further the recently suggested correlation between rigidity percolation in glassy covalent networks and fragility of corresponding melts. On an applied level, the present thrust provides a basis to determine their viability for optical applications.