摘要
通过共沉淀法制备Tm3+和Yb3+掺杂的NaYF4上转换发光材料。其中Tm3+和Yb3+的摩尔分数分别为0.01%,0.1%。在室温下测试了NaYF4∶Tm3+,Yb3+材料在300～1 100 nm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∶Tm3+,Yb3+材料为六方相晶体,其颗粒大小约为50～60 nm,产物结晶良好,含有少量杂相。在798 nm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Tm3+的激发态1G4到基态3H6的跃迁,绿光来源于Tm3+的1D2→3H5跃迁。
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 upconversion emission was observed when excited by 798 nm. The green and blue upconversion emission spectra were measured. Based on the experimental results the possible upconversion mechanism was analyzed. The main mechanism is the in-direct sensi-tization of Tm^3＋ and Yb^3＋. The blue emitting light results from the transition of^1G4→^3H6 of Tm^3＋ , green emitting light is from the transition of ^1D2→^3F4 of Tm^3＋. To our knowledge, there have not been similar works published domestieally and abroad. The struetural properties of the samples were characterized by X-ray dif- fraction （XRD） and scanning electron mieroseopy （SEM）. The results show that NaYF4： Tm^3＋ , Yb^3＋ prepared by co-precipitation method exhibits hexagonal crystal phase.
出处
《发光学报》
EI
CAS
CSCD
北大核心
2009年第2期195-200,共6页
Chinese Journal of Luminescence
基金
国家自然科学基金(20876002)
北京市自然科学基金(2082009
2091002)
北京市属高等学校人才强教计划资助项目
作者简介
孙家跃（1955-），男，辽宁抚顺人，教授，博士生导师，主要从事无机功能材料的研究。E-mail：sunjy@btbu．edu．cn
通讯联系人；E-mail：duhaiy@th．btbu．edu．cn，Tel：（010）68986213
