Thermal and mechanical properties of tellurite glasses for mid-IR molded glass lens applications

In the present study, zinc molybdenum tellurite glasses with the molar composition of (1−x)TeO2−yMoO3−xZnO and (1−x)TeO2−yMoO3−xZnO, where x = 10, 20, and 30 mol%, and y = 10 and 20 mol%, were prepared by a high temperature melt quenching technique and studied their thermal, thermo-mechanical and mechanical properties. From the thermal analysis, it was found that the glass transition (Tg), crystallization (Tx) and stability parameters slightly increased with increase in ZnO content in both series of glasses. Thermal expansion coefficient decreases from 16.56 to 14.67×10-6/K as the ZnO content increases from 10 to 30 mol%. Knoop hardness slightly decreases from 307 to 290 kgf/mm2 with increase in ZnO content from 10 to 30 mol% for 10 mol% of MoO3 content, whereas it increases for 20 mol% of MoO3. Based on the results, it concludes that the number of bridging oxygens and network compactness of tellurite matrix increased with increase in ZnO content varied from 10 to 30 mol%.