Temperature dependence of radiophotoluminescence in Ag-doped phosphate glasses containing different alkali metals

Abstract

Ag-doped phosphate glasses containing Na and Al cations have been used in radiophotoluminescence (RPL) dosimeters. The formation mechanism of RPL center (Ag2+ and ) in Ag-doped phosphate glasses, containing various cations, has unresolved issues. Herein, we investigated the mechanism of the RPL center formation in Ag-doped phosphate glasses from the viewpoints of temperature dependence and activation energy of RPL center formation. We estimated the activation energies of RPL center formation in Ag-doped phosphate glasses containing Na and Al (Na-Al/Ag), Na and K (Na-K/Ag), and Al and K (Al-K/Ag) cations. The activation energy of formation did not increase with the first ionization energy of the cations contained in the glasses. This result suggests that electrons are trapped not at cations but at negative ion vacancies before forming Furthermore, the activation energy of formation increased with increasing mean molecular volume as the distance between the electron trapping site and increases. On the other hand, the activation energy of formation decreased with increasing mean molecular volume which is the opposite of the result of Consideration of temperature dependence of RPL intensity, the intensity of the RPL corresponding to in Al-K/Ag increased slightly at 300 K from that at 25 K. In addition, the concentration at 25 K in Al-K/Ag was approximately half of that at 300 K. These results indicate that only holes trapped at shallow trap sites transfer to in Al-K/Ag.