【作者】 王云龙；

【导师】 徐衍岭；

【作者基本信息】 哈尔滨工业大学 ， 物理化学， 2013， 硕士

【摘要】 采用高温固相法制备了Ho³⁺、Tm³⁺和Yb³⁺离子掺杂的Zn_xCa_1-xWO₄多晶。其最佳基质成分为Zn_0.1Ca_0.9WO₄，最佳合成工艺为烧结温度1000℃，烧结时间3h。XRD分析表明掺杂的稀土离子未能改变基质的晶格结构。通过紫外吸收边的移动确定稀土离子在晶格中的占位规律。制备了Yb³⁺离子浓度为4mol％，Ho³⁺离子浓度为0.2³mol％的Zn_0.1Ca_0.9WO₄:Ho³⁺/Yb³⁺多晶。通过980nm光源激发，上转换光谱在545nm和659nm处有两个明显发射峰，分别对应Ho³⁺离子的⁵F₄/⁵S₂→⁵I₈绿光发射和⁵F₅→⁵I₈红光发射。实验结果表明上转换发光强度随着Ho³⁺离子浓度提高先增大后减小；功率曲线说明上转换绿光和红光均为两光子过程；绿光和红光的荧光寿命分别为67μs和106μs。结合功率曲线和荧光寿命分析了上转换绿光和红光发光机理。制备了Tm³⁺离子浓度为2mol％，Yb³⁺离子浓度为1⁸mol％的Zn_0.1Ca_0.9WO₄:Tm³⁺/Yb³⁺多晶。通过980nm光源激发，上转换光谱在473nm处有明显的发射峰，对应Tm³⁺离子的¹G₄→³H₆蓝光发射。实验结果表明上转换发光强度随着Yb³⁺离子浓度提高先增大后减小；功率曲线说明上转换蓝光以三光子过程为主；蓝光的荧光寿命为82μs。结合功率曲线和荧光寿命分析了上转换蓝光发光机理。采用正交实验研究了Zn_0.1Ca_0.9WO₄:Ho³⁺/Yb³⁺/Tm³⁺多晶的上转换发光性能。在980nm光源激发下，Zn_0.1Ca_0.9WO₄:Ho³⁺/Yb³⁺/Tm³⁺多晶上转换光谱在474nm、546nm和658nm处有三个明显发射峰，对应蓝绿红三色光，分别来自于Tm³⁺离子的¹G₄→³H₆能级跃迁， Ho³⁺离子的⁵F₄/⁵S₂→⁵I₈和⁵F₅→⁵I₈能级跃迁。实验结果表明，适当降低Tm³⁺离子浓度有利于上转换三色光强度的增加；减小Ho³⁺离子浓度能使上转换绿光强度降低，红光和蓝光强度增加。Zn_0.1Ca_0.9WO₄：0.6mol％Ho³⁺/0.5mol％Tm³⁺/4mol％Yb³⁺样品可以发出上转换白光，CIE坐标计算结果为（0.35,0.37），在白光发光范围内。功率曲线测试结果表明蓝光发射需要吸收三光子能量，绿光发射需要吸收两光子能量，红光发射需要吸收两光子或三光子能量。更多还原

【Abstract】 Zn_xCa_1-xWO₄: Ho³⁺/Tm³⁺/Yb³⁺polycrystals samples were prepared via hightemperature solid state method. Zn_0.1Ca_0.9WO₄was determined as the best matrixcomponents which was synthesized by sintering3h under1000℃. XRD analysisshowed that there was no effect of the dopant ions on the crystal structure. Using theshift of the ultraviolet assimilation borderline to confirm the regulation of therare-earth ions in the crystal structure.A series of Zn_0.1Ca_0.9WO₄: Ho³⁺/Yb³⁺samples with4mol％Yb³⁺ions and Ho³⁺ions from0.2mol％³mol％were prepared. The upconversion spectra of theZn_0.1Ca_0.9WO₄: Ho³⁺/Yb³⁺multi-crystals have two distinct emission peaks at546nmand658nm, which arise from the⁵F₄/⁵S₂→⁵I₈and⁵F₅→⁵I₈transitions of Ho³⁺. Theresult showed that the intensity of upconversion luminescence were first increased thendecreased with the increasing concentration of Ho³⁺ions. The pump dependenceindicated that the green and red upconversion emission both resulted from thetwo-photon process. The fluorescence lifetime of green and red light were67μs and106μs, respectively. Combined with the pump dependence and fluorescence lifetime,the green and red upconversion mechanism were analyzed.Zn_0.1Ca_0.9WO₄: Tm³⁺/Yb³⁺samples with2mol％Tm³⁺ions and Yb³⁺ions from1mol％⁸mol％were prepared. The upconversion spectra of the Zn_0.1Ca_0.9WO₄:Tm³⁺/Yb³⁺multi-crystals have a distinct emission peak at474nm, which arise fromthe¹G₄→³H₆transition of Tm³⁺. The result showed that the intensity of upconversionluminescence were first increased then decreased with the increasing concentration ofYb³⁺ions. The pump dependence indicated that the blue upconversion emissionresulted from the three-photon process. The fluorescence lifetime of the blue light were82μs. Combined with the pump dependence and fluorescence lifetime, the blueupconversion mechanism were analyzed.The upconversion luminescence properties of Zn_0.1Ca_0.9WO₄:Ho³⁺/Yb³⁺/Tm³⁺polycrystals were studied by orthogonal experiment. Under980nm excitation, the474nm,546nm, and658nm emission peaks are observed in the upconversion spectra ofZn_0.1Ca_0.9WO₄:Ho³⁺/Yb³⁺/Tm³⁺polycrystals. The blue luminescence is from1G4→3H6transition of Tm³⁺, and⁵F₄/⁵S₂→⁵I₈、⁵F₅→⁵I₈transitions of Ho³⁺emited the green andred luminescence respectively. The experimental results indicated that the decreasingconcentration of Tm³⁺was better for upconversion. The intensity of the green lightdecreased while the blue and red light increased with the decreasing concentration ofHo³⁺. Zn_0.1Ca_0.9WO₄：0.6mol％Ho³⁺/0.5mol％Tm³⁺/4mol％Yb³⁺sample emited white emission and CIE coordinate is （0.35,0.37） within the white light. The pumpdependence suggested that the blue upconversion emission was populated bythree-photon process, the green was two-photon process, the red was two and threephoton processes.更多还原