【作者】 肖生春；

【导师】 吕景文；

【作者基本信息】 长春理工大学 ， 材料物理与化学， 2013， 博士

【摘要】 稀土离子掺杂上转换发光材料在光通信、上转换激光、三维显示以及数据存储等领域已经得到广泛应用。但其存在声子能量高,上转换效率低,制备不方便,化学稳定性差,机械性能不高等不利因素,制约了其发展应用。近年来随着人们的深入研究,研制出一种性能稳定,上转换效率高的稀土掺杂发光玻璃材料：氟氧化物微晶玻璃。它兼顾了氧化物玻璃良好的物理化学稳定性和高强度机械性能等优点；同时通过可控热处理析晶析出氟化物晶相,具备氟化物玻璃较低声子能量的物理特性,稀土离子优先富集于氟化物晶相中,从而极大地提高了稀土离子的上转换发光效率,成为一种极具发展前景的稀土掺杂发光材料。本文采用一组新的配方制备了上转换氟氧化物微晶发光玻璃。实验所使用的原料分别为SiO2、BaF2、Bi2O3、AlF3、Sr(NO3)2和稀土氧化物Er2O3、Tm2O3、Ho2O3。通过差热分析,我们选择680℃左右温度作为热处理析晶温度；通过吸收谱和上转换荧光谱,热处理析晶时间定为2～4小时；通过X射线衍射实验,我们发现样品通过热处理形成了氟化物微晶。采用Judd-Ofelt理论对样品光谱进行了分析,拟合得到了强度参数Ω2、Ω4、Ω6；计算了样品的辐射寿命,跃迁几率,荧光分支比等光谱参数,并进行了分析比较,找到了最佳的稀土掺杂浓度。通过分析对比玻璃热处理前后的J-O强度参数,发现热处理后对应的Ω2和Ω4都明显降低,其中已Ω2降低最多,而Ω6数值稍有所提升；同时通过与其他上转换发光玻璃对比,发现玻璃样品的Ω2最小：表明该玻璃的共价性强,稀土离子结构和配位对称程度最低,更容易被激发,发射光谱强度有明显增强。制备了Yb3+与Er3+/Tm3+/Ho3+双掺、三掺和四掺氟氧化物微晶玻璃。在980nm激光激发下,分析了红色、蓝色和绿色上转换发光机理。主要有Yb3+离子与Er3+、Tm3+、Ho3+离子间的能量传递作用,还有稀土离子间的交叉弛豫作用。同时还分析了不同稀土浓度对上转换光强度的影响,对于双掺系统,Er3+离子上转换绿光最强,红光较弱,而蓝光最弱；Ho3+离子上转换红光最强,绿光较弱,蓝光最弱；Tm3+离子上转换蓝光极强,红光微弱,而绿光基本没有。由于稀土离子之间的交叉弛豫以及它们与Yb3+离子之间的能量反向传递,在多掺系统中,发光强度与稀土离子浓度间存在这样一种关系：随着Er3+离子浓度的增加,上转换绿光强度先增加后降低,红、蓝光强度都降低；随着Ho3+离子浓度的增加,上转换红光先增加后降低,绿光强度变化不大,而蓝光强度通常会急剧降低；随着Tm3+离子浓度的增加,上转换蓝光强度先增加后降低,红、蓝光强度都降低。所以根据输出光的要求可以调整稀土离子的浓度。当Er2O3、Ho3O3、 Tm2O3的掺杂浓度分别为0.5wt%、0.3wt%、0.1wt%时,能够实现上转换白光输出。更多还原

【Abstract】 Rare earth ions doped oxyfluoride upconversion luminescence material already own a wide application in optical communication, upconversion laser,3D display, and data storage, but also defects like high energy phonon, low efficiency of upconversion, inconvenience of production, chemical instability, and low mechanic performances. With the deep study of upconversion luminescence, there has been major development of rare earth ions doped oxyfluoride upconversion luminescence glass-ceramics in recent years. With the low phonon energy of fluoride glass’s physics properties, the good physical and chemical stability and high mechanical strength of oxide glass, precipitation can be achieved by controlled crystallization of fluoride crystal phase. Since the low phonon energy of fluoride crystal phase, the rare-earth ions concentrate in the fluoride crystal phase, which can greatly enhance the upconversion luminescence efficiency of rare-earth ions. As a result, the fluoride-oxide luminescent glasses are highly promising rare-earth doped luminescent materials.This thesis uses a new formula to produce oxyfluoride glass ceramics, with raw material like SiO2, BaF2, Bi2O3, AIF3, Sr(NO3)2and rare earth oxide Er2O3, Tm2O3, and HO2O3. Through analysis Differential Thermal Analysis,680℃is adopted as the heat treatment crystallization temperature; by absorption spectrum and upconversion fluorescence spectrum, the crystallization time is set to2-4hours; and oxyfluoride glass ceramics is produced through heat treatment after X-ray diffraction experiment.This thesis analyzed on the spectrum of samples with Judd-Ofelt theory, and obtained the intensity parameters Ω2、Ω4、Ω6. Analyzed and compared, the optimum doping concentration of the rare earth ion was concluded, with spectral parameters, like radioactive lifetimes of samples, transition probabilities, and fluorescence branching ratio etc. Comparing the J-O intensity parameters before and after the heat treatment,Ω2、Ω4decreased sharply, mostly Ω2, and Ω6increased a little. and with comparison with other upconversion luminescence glass, this sample is believed with a lowest Ω2value, which means this glass has the highest covalency, the lowest matching symmetricity as rare earth structure, more likely to be excited and with a high intensity of emission spectrum.A set of Yb3+, Er3+, Tm3+, Ho3+ions double, triple and quadruple doped oxyfluoride glass ceramics were prepared for the red blue, and green upconversion luminescence mechanism in980mm laser excitation, including the energy inter-transference among Yb3+Er3+、Tm3+、Ho3+, the cross relaxation among rare earth ions, and the influences of density of ions on optical upconversion intensity of the colors. As for double dope mode, Er3+causes highest upconversion of green light, weaker upconversion of red light and weakest upconversion of blue light; Ho3+causes highest of red light, weaker of green light, and weakest of blue; Tm3+causes highest of blue light, weaker of red, and almost no green light. As for multiple doping mode, with the cross relaxation of rare earth ions and the reverse energy transference with Yb3+, the luminescence intensity varies as:with increase of Er3+intensity, green light intensity increases first then decreases, and both red and green light intensity decrease; with increase of Ho3+, red light intensity increases first then decreases, green light intensity changes little, and blue light decreases sharply; with increase of Tm3+blue light intensity increases first then decreases, both red and blue light decrease. Therefore, with adjustment of rare earth ions intensity in Yb3+, Er3+, Tm3+, Ho3+quadruple mode, with dope intensity of Er2O3(0.5wt%), Ho2O3(0.3wt%), Tm2O3(0.1wt%), white light emission can be achieved.更多还原