Luminescent properties of Tb3+ doped sodium silica germanate glasses

Abstract

Tb3+-doped sodium silica germanate glasses were fabricated by conventional melt quenching technique with dopant concentrations of 0.3 %mol and 0.9 %mol. Their structural characteristics were analyzed by means of X-ray diffraction and Raman spectroscopy. The study of their optical properties was carried out through steady-state and time-resolved fluorescence spectroscopies. The emission spectra of both glasses are dominated by 5D4 → 7FJ manifold transitions. The most intense band, associated to 5D4 → 7F5 transition, shows a clear split into two peaks (545 nm 549 nm) due to crystal field splitting. The decay of Tb3+ emission at 458 nm exhibits a non-exponential evolution accompanied by a shortening of its lifetime as the concentration of Tb3+ increases, due to a non-radiative Tb3+-Tb3+ energy transfer through the cross-relaxation mechanism [5D3, 7F6] → [5D4, 7F0] between two terbium ions. The color coordinates at different excitation wavelengths lie in the yellow-green region of the Commission International de lˊEclairage chromaticity diagram. The results indicate that the studied glasses can be used in applications as solid-state lighting and display devices.