STABILITY STUDY ON HEATING AND DETERMINATION OF CRITICAL COOLING RATES OF FLUOROZIRCONATE GLASSES

In order to obtain a better understanding of the crystallization behav iour of fluorozirconate glasses (ZBLAN) different compositions from th e literature have been studied by differential thermal analysis. Therm al effects during heating of glass samples and cooling of glass melts have been considered. The effect of lead, yttrium and hafnium on glass stability is pointed out. Typical temperatures and parameters such as Hruby coefficients, H-r, H', and critical cooling rates, R(c), are gi ven. A procedure to determine experimental values of the critical cool ing rate is proposed.