中文摘要：

通过共沉淀法制备Tm^3＋和Yb^3＋掺杂的NaYF4上转换发光材料。其中Tm^3＋和Yb^3＋的摩尔分数分别为0．01％，0．1％。在室温下测试了NaYF4：Tm^3＋，Yb^3＋材料在300-1100nm的吸收光谱。利用X射线衍射（XRD），扫描电镜（SEM）测试了合成材料的物相结构和微观形貌。结果表明：NaYF4：Tm^3＋，Yb^3＋材料为六方相晶体，其颗粒大小约为50～60nm，产物结晶良好，含有少量杂相。在798nm近红外光激发下，测试了样品的上转换发光光谱。观察到了蓝、绿色上转换发光。讨论了上转换发光的可能机理，蓝光主要来源于Tm^3＋的激发态^1G4到基态^3H6的跃迁，绿光来源于Tm^3＋的^1D2→^3H5跃迁。

英文摘要：

The upconversion （UC） processes of infrared light to visible light of rare earth ions doped different hosts have been investigated extensively, due to their potential applications in some fields, such as solid-state lasers, display, communications, and so on. The recent researches emerging at the intersection of nanotech- nology and biotechnology are opening up a new period for the development of UC. As known, the controlled fabrication of a host with aimed structure is important for enhancing the upconversion efficiency, because the phonon energy of the host can affect the probabilities of non-radiative decay and the energy transfer. There-fore, it is necessary to choose a lattice with much lower phonon energy, which is benefit to the upconversion luminescence. Rare earth-doped hexagonal sodium yttrium fluoride （NaYF4） is a good host, which is known to be a very efficient near-infrared to visible upconverter. The hexagonal NaYF4 has low phonon energy. The structure of hexagonal phase gives rise to controversy about the cation sites and distribution. The trivalent thu- lium （Tm^3＋） is an ideal candidate for single wavelength NIR upconversion due to its ladder of nearly spaced equally energy levels that are multiples of the ^1G4→^3H6 transition. The development of compact blue lasers based on Tm^3＋ upconversion processes is nowadays widely studied mainly due to the potential of high perfor- mance OEM applications, such as biomedical and analytical instrumentation, display, photoprinting. In thu- lium doped media, the efficiency of this process is very low, but it was noticed that the mechanism could be made one or two orders of magnitude more efficient by using ytterbium （Yb^3＋）. In this paper, trivalent thu-lium （Tm^3＋） and yttebium （Yb^3＋） ions codoped NaYF4 were synthesized by co-precipitation method. The concentration of Tm^3＋ and Yb^3＋ are 0.01%, 0.1%, respectively. The on spectrum of NaYF4： Tm^3＋ , Yb^3＋ from 300 to 1 100 nm was measured at room temperature. The