Optical fiber-drawing temperature of fluorogallate glasses

The thermal properties and the crystallization behavior of fluorogallate-based glasses were analyzed. The kinetic nature of the glass transition 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 studied by using both isothermal and continuous heating regimes. The temperature 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 growth rates from which the time-temperature-transformation curves and the temperature-heating rate-transformation diagrams were constructed. The results obtained agree with experimental data and are discussed in the Light of minimizing the volume of crystals formed during fiber drawing.