Temperature effect on the glass forming ability of strontium tellurite and lead tellurite melts

Transparent glass-ceramic and crystalline samples of two systems: xSrO-(100-x)TeO2 (x = 7.5 and 8.5 mol%) and xPbO-(100-x)TeO2 (x = 15 and 20 mol%) were prepared by quenching their melts from different temperatures in the range of 650 °C to 950 °C. An intriguing effect of the temperature on the glass-forming ability (GFA) of strontium tellurite and lead tellurite melts is discovered. It is found that the melts solidify into transparent glass-ceramics on cooling from lower temperatures of 650–750 °C, however when the melts are cooled from higher temperatures in the range of 750–950 °C, the GFA decreases drastically and anti-glass and/or crystalline phases are produced on solidification. The high-temperature tellurite melts freeze faster into crystalline phases as compared to the melts at a lower temperature; the latter supercool and solidify into glassy phases. Strontium tellurite and lead tellurite melts show memory effects due to slow structural transformations which influence their GFA.