Annealing Of New Optical Borate Glasses: Ii, Change Of Refractive Index By Thermal Treatment

To establish the annealing schedule of the glass the refractive index at constant temperature and constant cooling rate was measured and compared with that of normal silicate glass. With constant cooling rate the final limiting refractive index is determined by the cooling rate when the holding temperature is higher than the fictive temperature. After the index departs from the (apparent) equilibrium line, however, the shape of the index-temperature curve is influenced by cooling rate and cannot be expressed by the same equation independent of cooling rate. This result differs from Ritlands conclusion. 16 figs