OPTICAL FIBER-DRAWING TEMPERATURE OF FLUOROGALLATE GLASSES

The thermal properties and the crystallization behavior of fluorogalla te-based glasses were analyzed. The kinetic nature of the glass transi tion was used to determine the temperature dependence of the viscosity and from it an estimation of the appropriate drawing temperature for an optical fiber was established. The crystallization kinetics were st udied by using both isothermal and continuous heating regimes. The tem perature range for nucleation was evaluated and for samples previously nucleated the activation energy of the growth process was found. The results were used to estimate the empirical nucleation and crystal gro wth rates from which the time-temperature-transformation curves and th e temperature-heating rate-transformation diagrams were constructed. T he results obtained agree with experimental data and are discussed in the Light of minimizing the volume of crystals formed during fiber dra wing.