On the problem of homogeneous nucleation in fluoride glasses

A technique for determining the conditions under which glasses containing large quantities of fluorides become unstable against homogeneous nucleation during annealing at the glass transition temperature, is described. Its application to a system containing MnF₂, one of the better glass-promoting fluorides, suggests that most fluoride glasses produced to date are unstable against nucleation at their glass transition temperatures. This accounts for the difficulty in fabricating low scattering loss fibers by normal techniques and emphasizes the importance of developing optimized compositions over study of other properties, for this type of application.