THERMAL-PROPERTIES AND CRYSTALLIZATION KINETICS OF NEW FLUORIDE GLASSES

The thermal properties and devitrification behaviour of new fluoride g lasses were determined by means of thermoanalytical techniques. The gl ass-forming and stability parameters have been defined and evaluated f rom the measured characteristic temperatures. The kinetics of devitrif ication of bulk glass samples was investigated by combining data obtai ned from both isothermal and constant-heating-rate techniques. The kin etic data were also used to construct the time-temperature-transformat ion (T-T-T) curves and temperature-heating rate-transformation (T-HR-T ) curves. These graphical illustrations emulate the thermal condition of glass preforms while awaiting fibre drawing. The results obtained a re compared with a standard fuorozirconate glass currently developed f or fibre optical applications.