Photoluminescence properties of Pr doped and Tb-Mg codoped CaSnO_3 with perovskite structure

摘要

In the survey of photoluminescence properties of rare-earth doped alkaline-earth stannates, CaSnO_3 was found to show intense white luminescence by Pr doping and green luminescence by Tb-Mg codoping. Pr doped CaSnO_3 showed not only a red emission line originating from the f-f transition from ~1D_2 to ~3H_4 state, which is observed in Pr doped CaTiO_3 or SrTiO_3, but also an intense blue-green line assignable to the f-f transition from ~3P_0 to ~3H_4 state in Pr~(3+) ions. Because of the mixture of the red and blue-green luminescence, the Pr doped CaSnO_3 was seen in white under uv excitation. Tb-Mg codoped CaSnO_3 showed a sharp green emission line derived from the f-f transition of from ~5D_4 to ~7F_5 state in Tb~(3+) ions along with other small emission lines. Tb-Mg codoping effectively enhanced the green luminescence of Tb~(3+) ions probably due to the local lattice distortion around Tb ions induced by the small Mg ions at Ca sites. The photoluminescence properties of Pr doped and Tb-Mg codoped ASnO_3 (A=Sr, Ba) and CaMO_3 (M=Ti, Zr) with perovskite structures were also examined and compared to understand the luminescence mechanisms in these materials.