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

Tb3+ doped materials exhibit strong emission in the green (D-5(4)) and weak emission in the UV-blue (D-5(3)) regions. The blue emission can occur from direct UV excitation or by excited state absorption, through D-5(4) 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 D-5(4) 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 D-5(4) energy level life-times.