【摘要】 利用水热法成功合成了不同形貌的稀土掺杂六方NaY0.95Yb0.03Er0.02F4,包括柱状、粒状、片状、管状等.通过XRD,SEM,TEM对合成样品的物相结构及晶粒形态进行了表征,探讨络合剂EDTA用量;表面活性剂CTAB,P123,十二烷基苯磺酸钠;热溶剂水、乙二醇、聚乙二醇对晶体生长方向的影响,并对不同形态样品进行上转换发光性能测试,分析晶粒形态对上转换发光强度与寿命的影响,结果显示晶粒越小发光强度越强,相当粒径的管状样品的发光强度比粒状的强,不同晶粒形态上转换的主要能量传递模式也不相同.研究结果可以指导我们可控合成适应实际应用需求的晶粒形态及优良上转换发光性能的材料.更多还原

【Abstract】 Hexagonal NaY0.95Yb0.03Er0.02F4 microcrystals with different morphologies were prepared by hydro-thermal syn-thesis with three controlling methods,including addition of different amount of EDTA,addition of different surfactant in-cluding CTAB,P123 and SDBS and using different thermal solvents including water,ethanediol and polyethyleneglycol.The synthesis method can be described as following: trivalent nitrate stock solutions of 1 mol/L with ratio 0.95/0.03/0.02 of Y3+/ Yb3+/Er3+were prepared by dissolving the corresponding metal oxide in concentrated nitric acid at elevated temperatures and label as A.Certain concentration solution of EDTA,P123,CTAB,SDBS,NaF,and NH4HF2 were prepared as candidate.In a typical procedure,a certain amount of EDTA,CTAB,P123,and SDBS were added into 20 mL A sulution.After vigorous stirring for 30 min,certain mol NaF was added drop by drop,the pH value of solution was adjusted to 3.0 by the addition of 1 mol/L HF or NaOH,and then stirring continued for 30 min.Then the emulsion mixture was moved to Teflon-lined autoclave and incubated in oven at 195 ℃ for 4 h.The products were washed by deionized water and ethanol three times respectively,and then dried in oven at 60 ℃.Phase structure and crystal morphologies were characterized by XRD(X-ray powder diffrac-tion),SEM(scanning electron microscope) and TEM(transmission electron microscope) methods.Analysis results indicate that the crystal growing direction changed from [001] to [100] and bond distances between F-and Y3+/ Yb3+/Er3+were enlarged while bond distance between F-and Na+ was reduced with the increasing EDTA amount.The crystal morphology was added as surfactant;crystal sizes and exposure lattice plane were also tuned with different thermal solvents.Crystal was not changed by adding CTAB surfactant compared with no surfactant adding sample,while microtubes were obtained when P123 was added as surfactant,and micrograins morphology mixed with some smaller hexagonal NaYF4 when SDBS growing mechanism of different morphologies was discussed in the manuscripture.Upconversion(UC) luminescence emis-sion spectra and decay time curves of different-morphological samples were obtained using Edinburgh instruments FSLP920 fluorescence spectrophotometer with 980 nm OPTEK OPO LASER excitation.The lifetimes of 521 and 541 nm emission were fitted by single exponential decay function.Luminescence property analysis results show the intensity and lifetime of spectra emission is interrelated with crystal morphology,the emission intensity is enhanced with reducing of the thickness of micrograins,and the intensity of the smallest microstick is the strongest among all the samples.The lifetime fitted results show the decay time constants and rising time constants are different of different-morphological NaY0.95Yb0.03Er0.02F4,indi-cating that their energy transfer models are different during UC emission.This manuscripture may be helpful for morphol-ogy-controllable synthesis of UC materials with super luminescence performance.更多还原