Elena Petracovschi

Positron Annihilation in IR Transmitting GeS2-Ga2S3 Glasses

Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in GeS2-Ga2S3 glasses affected by Ga additions. It is shown that Ga-related void sub-system plays a decisive role in positron trapping process, while the overall density variation is defined mainly by Ge-related sub-system. These results serve as basis for new characterization route for inner free-volume structure of these glasses.

Chalcogenide glasses for infrared optics: A new method of elaboration

Chalcogenide glasses based on selenium are since twenty years considered as a way to replace single-crystalline Germanium often used as lenses for thermal imaging devices. While they should be costless because of the lowest proportion of germanium, their way of synthesis combining high temperature and silica tubes maintain a high cost. In this paper, an alternative method to prepare chalcogenide glasses by using a combination of mechanical milling and spark plasma sintering is presented. The structure of amorphous powder obtained after several tens of hours of mechanical milling was compared using NMR and Raman to the structure of glass made using the conventional melt-quench technique, both presents identical thermo-mechanical properties and structure. Moreover, the effect of various contaminations during milling and sintering on the final transparency is put forward.

Positronics of IR transmitting chalcohalide glass-ceramics

Positron annihilation lifetime spectroscopy combined with Doppler broadening of annihilation radiation was applied to study free-volume entities in Ge-Ga-S glasses having different amount of CsCl additives. These results serve as a basis for new direction in the characterization of inner free-volume structure of chalcohalide glass-ceramics conditionally declared as Positronics.