采用水热法制备CdWO4 ∶Yb3+ ,Ho3+纳米晶, 运用X射线衍射、扫描电镜和光谱分析对制备样品的结构和发光性能进行了表征。结果表明: CdWO4 ∶Yb3+ ,Ho3+为单斜晶系, 平均晶粒尺寸约为29.782 7 nm。用980 nm激光激发样品获得了发射光谱, 位于552 nm和659 nm的发射峰分别对应于Ho3+离子的5F45S2→5I8和5F5→5I8的跃迁。根据泵浦功率和发光强度之间的双对数关系可知, 552 nm和659 nm的发射均属于双光子过程。稀土离子的浓度对样品的发光强度的影响较大, 结果表明:当Yb3+∶Ho3+离子的量比为5∶1且Ho3+摩尔分数为1.5%时, CdWO4 ∶Yb3+ , Ho3+纳米晶的上转换发光强度最大。

Yb3+, Ho3+ ions co-doped CdWO4 nano-crystals were synthesized by hydrothermal method. The characterization and structure of the samples were measured by X-ray powder diffractions (XRD), field emission scanning electron microscope (ESEM) and fluorescence spectrophotometer. The results show that CdWO4∶Yb3+, Ho3+ is monoclinic crystal system with the mean size of 29.782 7 nm. The emission spectra were obtained when the samples were excited by 980 nm semi-conductor laser. The green (552 nm) and red (659 nm) emission peaks are obviously observed, which are corresponding to the 5F45S2→5I8 and 5F5→5I8 transitions of Ho3+ ions. According to the relationship between pump power and luminescence intensity, the green and red peaks can be due to the double-photons absorption processes. The concentration of the rare earths could influence the luminescence intensity. The strongest peak was obtained when the mole fraction of Ho3+ is 1.5% and the ratio of n(Yb3+)∶n(Ho3+)=5∶1.