Effects of glass-forming histories on the crystallization kinetic of the 20Li2O–80TeO2 glass

Abstract In the present work, tellurite 20Li2O–80TeO2 glasses were prepared with identical nominal composition under different glass-forming histories to produce a stressed and stress-free samples. X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) techniques were used to study the effects of the glass-forming histories on the thermal and structural properties of these glasses. The γ-TeO2 (metastable), α-TeO2 and α-Li2Te2O5 phases were identified during the controlled devitrification in these glasses. The mestastable character of the γ-TeO2 phase was clearly observed in the glass under stress but this effect is not so clear in the stress-free glass. The γ-TeO2 and α-TeO2 phases crystallizes during the initial stages of crystallization in both studied glasses while the α-Li2Te2O5 phase crystallize in the final stages of the crystallization. The activation energies and Avrami exponent were calculated for both studied glasses with different particle size leading to E3 > E2 > E1 for stressed glass and E3 > E2 ≈ E1 for stress-free glass, where E1, E2 and E3 were associated to the γ-TeO2, α-TeO2 and α-Li2Te2O5 phases, respectively. The observed distinct n ¯ 1 n ¯ 2 n ¯ 3 in both glasses is an indicative that nucleation and growth takes place by more than one mechanism in the early stages of the crystallization.