Luminescent Properties of Rare-Earth-Metal Ion-Doped KLaNb2O7 with Layered Perovskite Structures

Rare-earth-metal ions (Pr 3+, Sm 3+, Eu 3+, Tb 3+, Dy 3+, and Er 3+ ) doped in KLaNb 2 O 7 with a layered perovskite structure showed photoluminescence by excitation of the two-dimensional host at 77 K. Dy 3+ - and Er 3+ -doped KLaNb 2 O 7 showed the luminescence of both rare-earth-metal ions and host. In contrast, Pr 3+ -, Sm 3+ -, Eu 3+ -, Tb 3+ -doped KLaNb 2 O 7 showed only the luminescence of their rare-earth-metal ions by host excitation, while the host luminescence was almost quenched. In the latter group, the characteristics of Tb 3+ - and Pr 3+ -doped KLaNb 2 O 7 with respect to the temperature dependence of photoluminescence, afterglows and thermoluminescence were different from those of the others, suggesting that the hole-trapping process by the Tb 3+ and Pr 3+ played an important role for the characteristic behaviors. On the other hand, Sm 3+ -doped KLaNb 2 O 7 showed bright photoluminescence and thermoluminescence as a unique characteristic of the KLaNb 2 O 7 system. In this process, Sm 3+ ions in the perovskite layers seem to work as electron-trapping sites.