不同波长激发下YLiF4：Er3+,Tm3+,Yb3+的发光

水热法合成了YLiF₄:Er³⁺,Tm³⁺,Yb³⁺,其中Er³⁺、Yb³⁺和Tm³⁺的摩尔分数分别为1%、1.5%和2%。当用355nm光激发时,其发光为蓝色,峰值位于450nm,对应于Tm³⁺的¹D₂→³F₄跃迁。用378nm激发时,发光为绿色,主要发光峰位于552nm。980nm光激发时,发光为白色,发光峰分别位于665(651),552(543),484,450nm处,并在648nm处还观察到了一个发光峰,其中最强的发射为红光。YLiF₄:Er³⁺,Tm³⁺,Yb³⁺的蓝光来源于Tm³⁺的激发态¹G₄到基态³H₆的跃迁,绿光来源于Er³⁺的⁴S_3/2和²H_11/2到基态⁴I_15/2的跃迁,红光既来源于Tm³⁺的¹G₄→³F₄的跃迁,也来源于Er³⁺的⁴F_9/2→⁴I_15/2的跃迁。在上转换发光中,还探测到了紫外光359nm的发射。监测665nm得到的激发光谱不同于监测552nm的激发光谱,在665nm的激发光谱中出现了对应Tm³⁺的¹G₄能级的峰。在双对数曲线中,蓝光484nm、绿光552nm和红光665nm的斜率分别为2.25、2.28和2.21,紫外光359nm的斜率为2.85。因此在980nm激发下,蓝光484nm、绿光552nm和红光665nm都是双光子过程,紫外光359nm的发射是三光子过程。

Emission of YLiF4: Er3 + , Tm3 + , Yb3 + Excited with Different Wavelength

The sample of YLiF₄:Er³⁺,Tm³⁺,Yb³⁺ is synthesized by hydrothermal method.The mol fraction of Er³⁺,Yb³⁺ and Tm³⁺ is 1%,1.5% and 2%,respectively.The emission of YLiF₄:Er³⁺,Tm³⁺,Yb³⁺ excited by 355 nm is blue light with the peak in 450 nm which comes from the transition of ¹D₂→³F₄ of Tm³⁺.After excited by 378 nm,YLiF₄:Er³⁺,Tm³⁺,Yb³⁺ emits green light with the main peak in 552 nm.The color of upconversion luminescence of YLiF₄:Er³⁺,Tm³⁺,Yb³⁺ excited by 980 nm is white color.The upconversion spectrum exhibits distinct emission peaks at 665(651),552(543),484 and 450 nm.There is another peak around in 648 nm.The strongest is the light with the wavelength of 665 nm(651 nm).The blue light comes from the transition of ¹G₄→³H₆ and ¹D₂→³F₄ of Tm³⁺.The green light results from the transition of ⁴S_3/2(²H_11/2)→⁴I_15/2 of Er³⁺.It is proved that the red light originates from the transition ¹G₄→³F₄ of Tm³⁺ and the transition of ⁴F_9/2→⁴I_15/2 of Er³⁺.The excitation spectrum monitored by 665 nm is different to that monitored by 552 nm.There is an excitation peak corresponding to the energy level ¹G₄ of Tm³⁺ in the excitation spectrum of 665 nm.But there is no corresponding peak in the excitation spectrum of 552 nm.It is concluded that there is energy transfer processes between Er³⁺ and Tm³⁺ ions.In the double-log coordinate system,the slope of the emission of 484,552 and 665 nm is 2.25,2.28 and 2.21,respectively.The slope of the emission of 359 nm is 2.85.According to this power law,The emission of 484,552 and 665 nm are all due to two photon process,while the emission of 359 nm is due to three photon process.