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Preparation and Characterization of Rare Earth Doped Barium Germanate Powders
Author: RenXiaoJiao
Tutor: YangKuiSheng
School: Changchun University of Science and Technology
Course: Materials Physics and Chemistry
Keywords: hydrothermal method up-conversion nanocrystals BaGe4O9
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Type: Master's thesis
Year: 2013
Downloads: 4
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Abstract
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The up-conversion nanocrystals of NaY(WO4)2:Yb3+,Er3+and NaY(WO4)2:Yb3+,Tm3+were synthesized by hydrothermal method in our work. These crystals were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The XRD and SEM analyses showed that these nanocrystals all belong to tetragonal crystal system and the particle size range from25nm to50nm and dispersed uniformly. The spectrum was measured with Hitachi F-4500spectrophotometer under980nm diode laser excitation. The results are as follows:The emission peaking of BaGe4O9:Yb3+,Er3+nanocrystal at412nm、525nm、548nm和659nm corresponding to2H9/2→4Il5/2,2H11/2→4I15/2,4S3/2→4I15/2and4F9/2→4115/2transitions of Er3+, respectively. The experiments show that the luminescence intensity is strongest when concentration ratio of Yb/Er is4:1with the concentration of Er3+ions is3mol%and treatment temperature is600℃.According to the relationship between the pump power and luminous intensity,412nm、525nm、548nm和659nm emission peak all belong to two-photon process. The energy transfer mechanism of Yb3+and Er3+ions in the sample were discussedThe emission peaking of BaGe4O9:Yb3+,Tm3+nanocrystal at367nm、458nm、478nm、650nm corresponding to1D2→3H6,1D2→3F4,1G4→3H6and1G4→3F4transitions of Tm3+. respectively. The results show that the luminous result is best when concentration ratio of Yb3+/Tm3+is5:1, with the concentration of Tm3+ions is2.0mol%and treatment temperature is700℃.367nm、458nm、478nm、650nm emission peak are the two-photon process, and the energy transfer mechanism of Yb3+and Tm3+ions in the sample were discussed.
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