Deduction of kinetics parameters in composition: Tellurite–phosphate–sodium oxide

Three samples from tellurophosphate glasses with the compositions (85 − x) TeO2·15P2O5·xNa2O with x   = 15, 20 and 25 mol% were prepared by a melting technique. The crystallization behavior and the kinetics of the glasses were investigated using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The mean value of the activation energy (〈Eg〉)(〈Eg〉) for structural relaxation decreases from 352 to 317 ± 5 kJ mol−1. Otherwise the activation energy for crystallization (〈Ec〉)(〈Ec〉) was calculated to increase from 164, 195 and 201 ± 5 kJ mol−1 with increasing Na2O concentration. The values of the Avrami exponents for the exothermic peaks are closed to 1.0 and 2.0. The crystalline phase Te2P2O9 was detected and it grow as sheets disperse in the matrix.

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