Crystallization Characteristics of ZrF₄-Based Fluoride Glasses in Cooling and Reheating Processes

Abstract

Crystallization kinetics of ZrF 4 -based fluoride glasses in melt-cooling and reheating processes have been investigated by calorimetry. Critical cooling rates for glass-formation are estimated using the relation between undercooling and cooling rate. Kinetic parameters of crystallization in reheating are obtained just above deformation temperatures using the Avrami equation. It has been found that a ZrF 4 -BaF 2 -LaF 3 -YF 3 -AlF 3 -LiF glass shows high stability against crystallization in both cooling and reheating. An optical fiber has been fabricated from this glass, having a loss of 3.8 dB/km at a wavelength of 2.55 µm.