Extending the Glass Formation of Alkali Tellurites

The physical properties of low alkali content tellurite glasses of composition xM2O.(1−x)TeO2 (0≤x≤0·35) have been previously collected in this laboratory. The twin-roller rapid quenching technique (cooling rate>105°C/s), used within a nitrogen environment, successfully and significantly extended the glass-forming range in the lithium and sodium tellurite systems. The upper range for modification has been extended from x=0·35 to 0·80 and up to x=0·625 for the lithium and sodium systems, respectively. In the K, Rb and Cs tellurites, the glass forming ranges were not increased. Glass transition temperature (Tg), crystallisation temperature (Tx), density, molar volume, packing fraction, ionic conductivity and Raman spectra were obtained for these glasses. These results showed structural changes as a function of composition and carbonate retention in the glasses as the amount of alkali modifier increased above x=0·5.