Abstract
The ionic conductivity of mol%50Li2O–50P2O5 melt quenched glass shows an anomalous increase after its glass transition temperature(Tg) around590 K. On further increasing the temperature gradually, the conductivity decreases owing to the devitrificationof Li2O–P2O5 glass. The evolution of devitrified crystallites was evidenced by XRD patterns. To understand thedevitrification process, isothermal and non-isothermal DSC studies have been carried out on mol%50Li2O–50P2O5 glass.Tg aswell as Tc values are found to increase monotonically with increasing heating rates. Variation ofTg as a function of heating rates has been investigated to evaluate the lower limiting temperature ofTg and the activation energy for structural relaxation. Results of the DSC studies indicate(i) single-stage bulk crystallization of the glass, with DSC traces exhibiting a single transition, (ii) an order parameter (Avrami constant) of2.8 ± 0.1,suggesting internal (bulk) crystallization of the glass, (iii) an activation energy for crystallization equalto 121.7 kJ mol−1 and (iv) the activation energy for structural relaxation,Eg, tobe 558.8 kJ mol−1. The crystallization mechanism is closely associated with the JMA model and theexperimental dataset have been fitted to a non-isothermal Avrami expression and theobtained parameters confirm the experimental results.
Published Version
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