RAMAN AND SPECTROSCOPIC STUDIES OF THE EARLY STEPS OF CRYSTALLIZATIONIN ZRF4-LAF3-ALF3-ERF3 GLASS

The effect of the thermal treatments at a temperatures much below the glass crystallization on the microstructure of ZrF4-based fluoride gla ss doped by Er3+ ions was studied. The glass characteristic temperatur es and the apparent activation energy for crystallization were estimat ed on the basis of differential thermal experiments. The crystallizati on of ErxLa1-xZr3F15 phase was detected in nearly transparent samples. Room temperature, Raman scattering spectra in the acoustic and optica l phonon regime as well as fluorescence of Er3+ ions in the infrared a nd visible region indicated a continuous structural modification of th e glassy matrix during heat treatment and crystallization initiation.