| Summary: | The kinetics of devitrification of fluoride glasses stabilized by magnesium fluoride when heated for some time between the glass transition and melting temperatures. The crystallization kinetics of AlF<sub>3</sub>-YF<sub>3</sub>-PbF<sub>2</sub>-CdF<sub>2</sub>-MgF<sub>2 </sub>glass prepared by melting the halide powders were studied by differential scanning calorimetry (DSC). The heating rate varied between 2 and 10 Kmim<sup>-1</sup>. Arami’s exponent (n) obtained by a non-isothermal method was 1.5 and 2.5 for a AlF<sub>3</sub>-YF<sub>3</sub>-PbF<sub>2</sub>-CdF<sub>2</sub>-xMgF<sub>2</sub> (x= 0, 5, 10) and n > 2.5 for a AlF<sub>3</sub>-YF<sub>3</sub>-PbF<sub>2</sub>-CdF<sub>2</sub>-15MgF<sub>2</sub>. According to the classical interpretation of n, these magnitudes correspond to diffusion controlled growth of crystals. The activation energies for crystallization, (E), varied from 195-326 KJ/mol. These results confirm the improved stability of these glasses, which could be used as base glasses for low phonon energy fluoride glass fibers.
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