Li + /Tm 3+ /Yb 3+ co-doped CaMoO 4 upconversion (UC) phosphor was prepared by complex citrate-gel method and UC luminescence properties were investigated. Li + /Tm 3+ /Yb 3+ co-doped CaMoO 4 has intense blue emission induced by 1 G 4 → 3 H 6 transition at 476 nm that is improved 10 times more than that of Li + undoped sample and weak red emission at 647 nm generated by 3 F 2 → 3 H 6 transition under excitation at 980 nm. The optimum doping concentration of Li + ions was investigated and UC mechanism of Li + /Tm 3+ /Yb 3+ co-doped CaMoO 4 was discussed in detail.

Controllable white upconversion (UC) luminescence was obtained from Tm3+/Ho3+/Yb3+-codoped CaWO4. Under the excitation of a 980 nm single wavelength laser diode, the Tm3+/Ho3+/Yb3+-codoped CaWO4 exhibited bright white UC luminescence composed of blue emission from Tm3+ and green and red emissions from Ho3+ visible to the naked eye. The intensity ratios of green, red, and blue UC emissions varied with Tm3+/Ho3+ concentrations, which can control white UC emission ranging from the cool to the warm region. Various white UC colors can be easily changed by adjusting the Tm3+/Ho3+ concentrations in the CaWO4 matrix.

No abstract

No abstract