The effect of silica content on the luminescence properties of Tb3+-doped calcium aluminosilicate glasses

Tb3+ doped materials exhibit strong emission in the green (5D4) and weak emission in the UV-blue (5D3) regions. The blue emission can occur from direct UV excitation or by excited state absorption, through 5D4 metastable level. In this paper, we investigate the effect of silica content on the spectroscopic properties of the Tb3+ doped calcium aluminosilicate glasses. The low silica calcium aluminosilicate glass (LSCAS) and calcium aluminosilicate glass (CAS) doped with 0.5 wt% of Tb3+ were prepared and characterized through absorption, excitation, Stokes emission, upconversion emission and 5D4 lifetime decay measurements. The green luminescence in the LSCAS glass presented a fast quenching. The silica influence on this behavior was discussed and a comprehensive interpretation is presented, correlating the Tb3+ luminescence behavior with the silica concentration. Additionally, we analyze the excited state absorption effect on fluorescence transients to 5D4 energy level lifetimes.