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 (T_g), crystallisation temperature (T_x), 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. [ABSTRACT FROM AUTHOR]