Radiation Modified Chalcogenide Glasses Tested With Positron Lifetime Annihilation Spectroscopy Technique

It is shown that only under coordinated topological defects can be satisfactorily tested with positron annihilation lifetime spectroscopy (PALS) applied to high energy irradiated chalcogenide glasses having 2-, 3- and 4-fold coordinated atoms within structural network. In the case of negatively charged sulphur and arsenic atoms in Ge-As-S system, the excess of free volume is great enough to be detectable as an additional input in the second defect related channel of positron trapping, while under coordinated germanium atoms in Ge-Sb-S system are practically undetectable with this technique because of low associated free volume.