Le Han,Jiaqiang Liu,Peng Liu,Bohan Li,Xianliang Li,Yan Xu
Ratiometric fluorescent sensing materials based on dual-emissive luminescent centers have been widely researched due to their highly stable self-calibrating monitoring performance. In this work, Eu 3+ , Tb 3+ co-doped gadolinium molybdate [Gd 2 (MoO 4 ) 3 ] phosphors were successfully prepared through a facile precipitation and a following heat treatment process. Dual-emissive Gd 2 (MoO 4 ) 3 : Eu 3+ , Tb 3+ phosphor showed characteristic emission peaks at 592, 617, and 703 nm corresponding to the transitions of 5 D 0 – 7 F 1 , 5 D 0 – 7 F 2 and 5 D 0 – 7 F 4 for Eu 3+ ions, and the other emissions at 488 and 543 nm were ascribed to 5 D 4 – 7 F 6 and 5 D 4 – 7 F 5 transitions for Tb 3+ , respectively. The temperature sensitivities of Gd 2 (MoO 4 ) 3 : Eu 3+ , Tb 3+ based on a multimode fluorescence intensity ratio (FIR) technique were investigated for monitoring temperature changes in the range of 80–450 K. The maximum relative sensitivities of the four modes of FIR (I Tb 3+ /I Eu 3+ ) techniques were successfully achieved with range of 0.37–0.50% K −1 . The results also demonstrated the high reversibility of Gd 2 (MoO 4 ) 3 : Eu 3+ , Tb 3+ phosphor used as a self-calibrating thermometer for thermal-sensing application.
The nearly pure green and red emissions of Ho 3+ /Yb 3+ co-doped Gd 2 (MoO 4 ) 3 were realized by tri-doping Eu 3+ and Ce 3+ , respectively. The Ho 3+ /Yb 3+ co-doped Gd 2 (MoO 4 ) 3 powder, radiating intense green and red emissions, was prepared by a typical sol-gel method. Under the excitation of 980 nm laser, the red-to-green ratio was tuned from 0.2 to 4 as the concentration of Eu 3+ changed from 6 to 0 mol%, attributed to the energy transfer processes between Ho 3+ and Eu 3+ . Meanwhile, the red-to-green ratio altered from 4 to 20 as the concentration of Ce 3+ changed from 0 to 20 mol% via the cross relaxing processes between Ho 3+ and Ce 3+ . The prepared phosphors, possessing large tuning range of red-to-green ratio and resisting high temperature, can be potentially applied to colorful display and solid-state lighting.
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