Crystallization processes in Ge-Ga-Se glasses studied with positron annihilation technique

The positron annihilation lifetime spectroscopy was applied to study controlled crystallization processes in 80GeSe₂-20Ga₂Se₃ chalcogenide glass, which was thermally treated at 380°C for 10, 50 and 100 h. It is shown that the structural changes caused by crystallization can be adequately described by positron trapping modes determined within two-state model. The observed changes in defect-related component in the fit of experimental positron lifetime spectra for annealed glasses testifies in a favour of structural fragmentation of larger free volume entities into smaller ones with preceding nucleation in the initial stage of thermal annealing.