Preparation And Fluorescence Properties Of Rare Earth Doped Fluoride Nanomaterials

This paper mainly researched on the fluoride nano materials which has the conversion luminescence performance. In order to solve the mismatch problem between silicon solar cells and the solar spectrum, we will prepare a series of fluoride nano materials with rare earth ions and improve the photoelectric conversion efficiency of solar cells by down-conversion.CeF3:x%Tb3+-y%Yb3+ nanoparticles have been prepared by the microwave assisted heating hydrothermal treatment (M-H). The SEM images showed that morphology of the samples with different fluorine source. When put KBF4 as fluorine source, the morphology of the sample is wafer. The thickness of the sample is about 50nm and the diameter is about 600nm. It has no reunion phenomenon when put NH4F as fluorine source. Excitation and emission spectra of various at room temperature are shown that the samples can absorb the ultraviolet light around a broad band from 250 nm to 280 nm, then emits light at 300 nm which corresponds to the transitions from 5D to 4F of Ce3+,480 nm,540 nm,583 nm,620 nm which correspond to the transitions from 5D4 to7 F6,5,4,3 of Tb3+,973 nm which corresponds to the transitions from 2F5/2-2F7/2 of Yb3+. When added a small amount of Tb3+, the near infrared irradiation of Yb3+ has an obvious enhancement. The energy mainly comes from two aspects:the direct energy transfer between Ce3+ and Yb3+and the energy transfer from Ce3+ to Tb3+ to Yb3+.Highly uniform and well-dispersed CaF2 microsphere with tunable particles size has been successfully synthesized by a facile hydrothermal process. We can control the morphology of the sample by changing the conditions of the reaction process. The morphology can be changed to hollow sphere by change the amount of complexing agent EDTA. The size of the samples increases from 100 nm to 900 nm when the pH value varies from 3 to 8 and become to solid particles. The conditions for the experiment:160℃,5h,Nca(NO3)2:NEDTA=1:1-7,pH=6.We studied and analyzed the luminescence properties of CaF2 nano phosphor with different rare earth ions doped. Obviously energy transfer was occurred in Ce3+ and Yb3+ doped CaF2 samples. There are strongly emission spectra at 1000 nm. The energy was from Ce3+ ions to Yb3+ ions. But the near-infrared light turned down in Ce3+, Tb3+ and Yb3+ doped samples. The main reason is that there is a competitive relationship between Tb3+ and Yb3+ ions in CaF2 samples and Ce3+ ions will transmit the limited energy to Tb3+ and Yb3+ ions. The uv-visible absorption spectra have a great absorption at 300 nm and correspond to the excitation spectra.