STUDY OF FLUORIDE GLASSES DEVITRIFICATION-BASED MAGNESIUM

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 AlF3-YF3-PbF2-CdF2-MgF2 glass prepared by melting the halide powders were studied by differential scanning calorimetry (DSC). The heating rate varied between 2 and 10 Kmim-1. Arami’s exponent (n) obtained by a non-isothermal method was 1.5 and 2.5 for a AlF3-YF3-PbF2-CdF2-xMgF2 (x= 0, 5, 10) and n > 2.5 for a AlF3-YF3-PbF2-CdF2-15MgF2. 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.

• crystallization kinetics, glass transition, DSC, Avrami’s exponent (n), activation energies (E).

• crystallization kinetics, glass transition, DSC, Avrami’s exponent (n), activation energies (E).