Impact of temperature on excitation, emission and cross-relaxation processes of terbium ions in GGAG single crystal

Terbium ions in Gd3Ga3Al2O12 (GGAG) single crystal exhibit strong luminescence originated in the 5D3 and 5D4 multiplets. The decay time of the 5D3 state is 1072 μs and 724 μs at 5 K and 300 K, respectively. The time dependence of luminescence originated from the 5D4 multiplet is consistent with single exponential decay, with lifetime values 3579 μs at low temperature and 2902 μs at 300 K. The non-exponential decay curves have been fitted in the frame of Inokuti-Hirayama model, indicating that the dipole-dipole interaction plays an important role in the fluorescence quenching of the 5D3 level. The calculated R0 parameter values are equal to 11.56 Å and 12.86 Å for 5 and K 300 K, respectively. The positions of multiplets up to 40000 cm−1 are determined employing the f-shell empirical programs. CIE 1931 coordinates are x = 0.298 , y = 0.664 (green) at 5 K and x = 0.360,  y = 0.538 (yellowish green) at 300 K.