STUDY OF FLUORIDE GLASSES DEVITRIFICATION-BASED MAGNESIUM

• Main Authors: C. Benhamideche, A. Boutarfaia, M. Poulain
• Format: Article
• Language: English
• Published: El Oued University 2015-07-01
• Series: Journal of Fundamental and Applied Sciences
• Subjects: crystallization kinetics, glass transition, DSC, Avrami’s exponent (n), activation energies (E).
• Online Access: http://jfas.info/index.php/jfas/article/view/90

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-MgF₂glass 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.