Effect of silver concentration on the silver-activated phosphate glass

The effects of silver concentration on the structure and properties of silver-activated phosphate glasses, with the nominal molar compositions xAg2O·(1 − x)(30Na2O·10Al2O3·60P2O5) and 0 ≤ x ≤ 10 mol%, were studied. Increasing the Ag2O-content decreases the glass transition temperature (Tg), increases the thermal expansion coefficient (TEC) and increases the glass dissolution rate in water. 31P nuclear magnetic resonance (NMR) and Raman spectroscopies indicate that the addition of Ag2O leads to the formation of chain-terminating P-tetrahedra, and 27Al NMR spectra indicate that Al-octahedra are the preferred structural moiety. Optical spectroscopy indicates that Ag2O-additions shift the UV-absorption edge to longer wavelengths. Irradiating glasses with ≤1.0 mol% Ag2O with 60Co γ-rays creates a photoluminescence (PL) center that emits near 605 nm when excited with UV light (337.1 nm). The intensity of this PL center is proportional to the radiation dosage (up to 200 Gy), and the relative sensitivity is maximized in glasses with 0.05 mol% Ag2O. When x > 1 mol% Ag2O, a second PL center, emitting at 470 nm, is activated. The formation of this second PL center is associated with the loss of radiation sensitivity for glasses with greater Ag2O-contents.