Up-conversion Mechanisms Of Samples Based On Bi₂O₃ And NaYF₄

Owing to the important applications in solid-state lasers, display devices, optical amplifiers and so on, up-conversion luminescence have attracted a great deal of attentions. In this dissertation, two kinds of rare earth doped materials based on oxide and fluoride respectively were fabricated by different synthetic methods. According to the emission spectra of the materials at 980nm excitation, the characteristics and the up-conversion mechanisms of the luminescence were studied. In the meanwhile the dependence of the emission performance of the samples on the synthetic method as well as the doping of rare earth ions were discussed. This paper consists of five chapters, firstly expounding the background and the foundational theories, and then introducing the author'work during the course of acquiring the Master's degree.In the first and second chapters of the dissertation, the history of the development and the Hotpoint of this filed were summarized briefly. The widely studied material systems that the up-conversion samples based on were presented. The preparation technology, potential applications and research methods were reviewed. The urgent problems which have not been solved in the studies of up-conversion as well as the possible way to solve them were shown. The basic theories and the up-conversion mechanisms were discussed.In chapter 3, Er3+/Yb3+ co-doped samples of red predominating emissions based on Bi2O3 that were prepared though high temperature solid-state reaction displays that the intensity ratio of red emission to green emission is higher than that of fluoride, and the properties of up-converted emissions under 980nm excitation of the samples were also dealt with.In chapter 4, a group of NaYF4:Yb3+,Tm3+ samples were prepared by high temperature solid-state reaction and Precipitation method, respectively. The effects of Yb3+ concentration on emission intensities were investigated, and the optimized Yb3+ concentration was obtained. From the comparison of the emission intensities of the samples with the same compositions fabricated by different synthetic methods, a conclusion can be drawn that the sample synthesized by Precipitation method is much better than that synthesized by high temperature solid-state reaction.Based on the investigation of chapter 4, the NaYF4:Er3+,Yb3+,Tm3+ samples were prepared by Precipitation method. When the concentration of Tm3+ changes from 0 to 0.6mol%, we found that the intensity of up-conversion luminescence decreases...