Fluorescence properties and relaxation processes of Tb3+ ions in ZnCl2-based glasses

60ZnCl2–20KCl–20BaCl2–xTbCl3 glasses (x = 0.10, 0.25, 0.50, 0.75, 1.00, and 1.25) were prepared by melt-quenching method, and Tb3+ fluorescence properties were investigated under 355 nm excitation. Regardless of x values, the electrons that were relaxed from the 5D3 to 5D4 level of Tb3+ ions by the multiphonon relaxation, were repressed to 28% of all the excited electrons because the ZnCl2-based glass had much lower phonon energy than oxide glasses. For 0 < x ≤ 0.34, the cross relaxation, (5D3 → 5D4) → (7F0 ← 7F6), was repressed, and consequently 72% and 28% of all the excited electrons were radiatively relaxed by the 5D3 → 7FJ (J = 6, 5, 4, 3, and 2) and 5D4 → 7FJ (J = 6, 5, 4, and 3) transitions, respectively. The lifetimes of the 5D3 and 5D4 initial levels were obtained to be 1.1 and 2.1 ms, respectively.