【作者】 吴尤娜；

【导师】 熊兆贤；

【作者基本信息】 厦门大学 ， 材料学， 2008， 硕士

【摘要】 本论文主要采用固相法制备Er³⁺／Yb³⁺离子掺杂的复合氟化物、Tm³⁺／Yb³⁺离子掺杂的复合氟化物、以及Er³⁺／Yb³⁺离子掺杂的氯氧化物和氟氧化物的上转换荧光粉，系统探讨离子掺杂浓度、荧光粉基质材料以及热处理工艺等对荧光粉性能的影响，并对影响上转换荧光粉性能的发光机理进行初步探讨。采用固相法制备可由980nm激光器上转换用绿色荧光粉NaYF₄：Er³⁺／Yb³⁺，通过两步法制备高纯度的六方相NaYF₄，并改变激活剂Er³⁺离子浓度和敏化剂Yb³⁺离子浓度，调节绿光和红光的相对强度比，得到高纯度的绿色荧光粉；比较了NaF和Na₂SiF₆两种不同原料对荧光粉性能的影响，发现用NaF制备样品的发光强度比用Na₂SiF₆的高，故选用NaF作为原料之一；采用不同的热处理工艺改善荧光粉的发光性能，发现在575℃保温8h后的荧光粉绿色发光最强，650℃热处理后样品出现由六方相向立方相转变，立方相的出现使荧光强度下降很多；为进一步优化NaYF₄：Er³⁺／Yb³⁺的荧光性能，采用正交实验对Er³⁺和Yb³⁺的取代量、热处理温度及保温时间优化后，分别掺入Yb³⁺离子和Er³⁺离子为20mol％和1mol％并在600℃保温6h，获得了最佳的绿色发光强度。采用固相法制备可由980nm激光器上转换用蓝色荧光粉NaYF₄：Tm³⁺／Yb³⁺，改变激活剂Tm³⁺离子浓度和敏化剂Yb³⁺离子浓度，调节蓝光和红光的相对强度比值，得到高纯度发光的蓝色荧光粉；还直接采用敏化剂做基质制备NaYbF₄：Tm荧光粉，并对比了NaYF₄：Tm³⁺／Yb³⁺和NaYbF₄：Tm两类荧光粉的上转换发光性能，NaYbF₄：Tm体系中Tm³⁺离子最佳浓度为0．4mol％，相比NaYF₄：Yb_0．30,Tmx体系中Tm³⁺的最佳浓度量上升，而且样品NaYF₄：Yb_0．4,Tm_0．002的蓝光发射强度大于NaYbF₄：Tm_0．004。采用固相法制备YOCl：Yb,Er和YOF：Yb,Er体系的红色上转换荧光粉，发现氧原子引入后，样品的红光发射强度明显强于绿光；在YOCl：Yb,Er体系中，Er³⁺离子和Yb³⁺的取代量分别为2mol％和20mol％时，红光的发光强度最强；由于氯氧化物的荧光性能不稳定，本论文又研制了Er³⁺／Yb³⁺共掺杂YF₃-YOF荧光粉，纯相YF₃：Yb_0.2，Er_0．02的发光强度很低，随着YF₃量减小而YOF量的增多，红光的强度不断增大，红绿光的比值也不断增大，当样品为纯YOF时，红光强度达到最大，其红绿光比值为3．75。针对实验中出现的影响上转换荧光性能的因素，本论文最后部分从晶体结构、能带理论、荧光光谱对其发光机理进行一定程度的探讨。更多还原

【Abstract】 In this thesis, several kinds of phosphors were synthesized via solid-state reaction method, including rare earth ion Er³⁺/Yb³⁺ co-doped sodium yttrium fluoride based green emitting upconversion phosphor, Tm³⁺/Yb³⁺ co-doped sodium yttrium fluoride based blue emitting upconversion phosphor, Er³⁺/Yb³⁺ co-doped YOCl and YOF based red emitting upconversion phosphor. It was systematically discussed for the effect of rare earth ion concentration, the chemical structure of the host lattices, heating temperature and holding time on the luminescent properties.A kind of upconversion phosphor for 980nm LD exciting in which pure hexagonal NaYF4:Er³⁺/Yb³⁺ was obtained developed in two stages via solid-state reaction route under reducing atmospheres. With changing Er and Yb concentration, the green emission intensity increases with respect to the red intensity. The properties of two kinds of phosphors were compared with NaF and Na₂Sif₆ as reagents, respectively. It was found that luminescent properties of the samples prepared with NaF were better. The result showed that heating temperature and holding time have significant influence on the properties of the phosphor, and the best green upconversion samples were obtained with heating temperature at 575℃for 8h. However, as heating temperature increase to 650℃, cubic NaYF₄ was observed with diffraction and the green emission intensity were decreased due to the occurrence of the cubic NaYF₄. In order to improve the luminescent properties of NaYF₄: Er³⁺/Yb³⁺ further, the orthogonal design of L₉（3⁴） was applied. In the experiments, four factors of the Er³⁺ concentration, Yb³⁺ concentration, heating time and holding time were considered, and the result showed that NaYF₄ phosphor doped with 1mol%Er³⁺ and 20mol%Yb³⁺, and heated at 600℃for 6h, had the optimal green emission.Tm³⁺/Yb³⁺ co-doped NaYF₄ phosphor with upconversion blue emitting was synthesized via the solid-state reaction. With changing Tm and Yb concentration, the blue emission intensity increases with respect to the red intensity. Comparing the upconversion properties between hexagonal NaYbF₄:Tm³⁺ and NaYF₄:Tm³⁺/Yb³⁺, the optimal doping level was 0.2mol% of Tm³⁺ doping NaYF₄ as well as 0.4mol% of Tm³⁺ doping NaYbF₄; and the blue emission of NaYF4:Tm_0.002³⁺,Yb_0.4³⁺ was higher and purer than that of NaYbF₄:Tm_0.004³⁺.As the emission of red transition was better in the samples with existence of oxides, YOCl:Yb,Er and YOF:Yb,Er phosphors were studied with the solid-state reaction method. In the YOCl:Yb,Er system, strongest red emission was obtained doped with 2mol% Er³⁺ and 20mol% Yb³⁺. Due to unstable upconversion properties of Y0C1 phosphors, Er³⁺/Yb³⁺ co-doped YF₃-YOF phosphors were chosen. YF₃:Yb³⁺/Er³⁺ behavied the lowest emission intensity and the smallest ratio of red to green intensity. When the content of YOF phase was larger, the red emission intensity increased with respect to the green intensity and, the pure YOF phosphor co-doped with Er³⁺/Yb³⁺ showed the highest red emission.更多还原