THE EFFECT OF RARE-EARTH IONS ON THE THERMAL-STABILITY OF ALF3-BASED GLASSES

The effect of rare earth ions on the thermal stability of AlF3-based g lasses has been investigated. Different concentrations of NdF3, ErF3 a nd PrF3 ranging from 0.25 to 2.0 wt% have been added to a well charact erized base glass. Differential scanning calorimetry (DSC) measurement s were carried out to determine the time-temperature-transformation (T TT) curves, critical cooling rates and Hruby parameters for both the b ase glass as well as for the selectively doped glasses. It was found t hat the thermal stability of AlF3-based glasses actually increased fol lowing the addition of the above rare earth ions up to certain concent rations and then started to gradually decrease but still remained high er than the original base glass. This behavior of AlF3-based glasses i s in contrast to those based on ZrF4 and may offer certain advantages in the fabrication of active fiber devices.