摘要
Nano-sized CaMoO4 phosphors tri-doped with Er3＋, Yb3＋and Tm3＋ions were successfully synthesized by sol-gel method. Intense blue emission from Tm3＋ions was observed upon excitation of 1532 nm infrared light in Er-Yb-Tm system, while this blue upconversion could not be achieved with the absence of Yb3＋ions in Er-Tm co-doped sample. In order to understand this upconver-sion process, the upconversion spectra in these samples were investigated, and the possible mechanism was proposed based on ex-perimental results. It showed that two different energy transfer from Er3＋to Tm3＋existed simultaneously in Er-Yb-Tm system, the one-step direct energy transfer from Er3＋to Tm3＋, and the two-step Er3＋→Yb3＋→Tm3＋energy transfer. In particular, the 1G4 state of Tm3＋could only be populated from the 3H4 state by cross-relaxation with an excited Yb3＋ion, producing blue emission of Tm3＋. In this upconversion process, Yb3＋ions acted as an energy transfer bridge between Er3＋and Tm3＋, which also meant that the upconver-sion of other rare-earth ions under the excitation of 1532 nm was possible with the presence of Er3＋and Yb3＋.
Nano-sized CaMoO4 phosphors tri-doped with Er3＋, Yb3＋and Tm3＋ions were successfully synthesized by sol-gel method. Intense blue emission from Tm3＋ions was observed upon excitation of 1532 nm infrared light in Er-Yb-Tm system, while this blue upconversion could not be achieved with the absence of Yb3＋ions in Er-Tm co-doped sample. In order to understand this upconver-sion process, the upconversion spectra in these samples were investigated, and the possible mechanism was proposed based on ex-perimental results. It showed that two different energy transfer from Er3＋to Tm3＋existed simultaneously in Er-Yb-Tm system, the one-step direct energy transfer from Er3＋to Tm3＋, and the two-step Er3＋→Yb3＋→Tm3＋energy transfer. In particular, the 1G4 state of Tm3＋could only be populated from the 3H4 state by cross-relaxation with an excited Yb3＋ion, producing blue emission of Tm3＋. In this upconversion process, Yb3＋ions acted as an energy transfer bridge between Er3＋and Tm3＋, which also meant that the upconver-sion of other rare-earth ions under the excitation of 1532 nm was possible with the presence of Er3＋and Yb3＋.
基金
Project supported by the National Natural Science Foundation of China(11204292,11274299,11311120047,11374291,11404321)
Anhui Provincial Natural Science Foundation(1308085QE75)
