SrZnO₂及其掺杂新型荧光体的合成与发光性能研究

【作者】 周春蕾；

【导师】 余锡宾；

【作者基本信息】 上海师范大学 ， 应用化学， 2006， 硕士

【摘要】 本文从SrZnO₂的合成方法、发光性能、发光机理、掺杂SrZnO₂荧光体等方面，综述了SrZnO₂及掺杂的研究进展。首次采用柠檬酸溶胶凝胶法成功合成了SrZnO₂及稀土离子掺杂荧光粉。应用X射线衍射、拉曼光谱、红外光谱、热重分析、紫外-可见吸收光谱、荧光光谱、透射电镜等先进仪器对材料进行了表征，得到以下主要结论： 采用柠檬酸溶胶凝胶法成功地合成SrZnO₂荧光材料，粉体呈浅绿色，所含杂相极少，颗粒呈棒状，平均长度在500nm左右，宽度在30nm左右。该样品在380nm激发下，发出很强的绿色荧光，发射主峰位于545nm附近。当煅烧温度为1000℃，柠檬酸与金属离子的比为3：1，起始溶液的pH值为5时，发光强度达最大。该材料可用于LED照明绿色荧光粉等领域。 荧光体的紫外光谱和激发光谱显示SrZnO₂是一种新型半导体材料，它的发光来源于材料中氧空位（Vo）缺陷发光。论文还研究了Sr／Zn比例对SrZnO₂荧光体发光性能的影响。当Sr／Zn比例达到0.8:1时，荧光强度达到最大。SrO过量时SrZnO₂的荧光峰位发生蓝移，ZnO过量时SrZnO₂的荧光峰位发生红移。 通过TEM图，本文发现用柠檬酸溶胶凝胶法制得的样品在不同烧结温度下呈现不同的形貌。随着温度的升高，形貌由喷射状纳米束转变为针状再转变为棒状后又分解为纳米束。 本文详细研究了钐离子掺杂SrZnO₂荧光体的发光性能、格位取代、浓度猝灭、能量传递以及共掺杂碱金属（Li,Na,K）离子对SrZnO₂:Sm³⁺发光性能的影响。 制得的SrZnO₂:Sm³⁺荧光粉体为白色，粒径微细。SrZnO₂:Sm³⁺荧光体的激发光谱分为两部分：1、峰值位于413nm锐线峰和主峰位于262nm较宽的激发带，前者属于Sm³⁺离子的f→f跃迁，后者来源于Sm³⁺—O^2-的电荷跃迁（CTB），在SrZnO₂中Sm³⁺的f→f跃迁强度大于CTB的强度；2、主峰位于380nm左右强度较弱的宽带激发峰属于SrZnO₂吸收。 在262或413nm激发下出现四组发射峰：568nm(⁵G_5／2→⁶H_5／2)，607nm(⁵G_5／2→⁶H_7／2)，655nm(⁵G_5／2→⁶H_9／2)，705nm(⁵G_5／2→⁶H_11／2)。四组发射峰中，位于607nm附近发射峰的强度最大。其中⁵G_5／2→⁶H_9／2的跃迁属于禁阻的电偶极跃迁，这组发射峰的出现表明Sm³⁺的格位对称性有所降低。进一步研究表明，Sm³⁺离子进入SrZnO₂更多还原

【Abstract】 In this paper, from the preparation method to photoluminescence properties and luminescence mechanism, the research progress of pure and doped SrZnO₂ phosphors were reviewed. Through optimizing preparation conditions, pure and doped SrZnO₂ phosphors, were successfully synthesized by citrate-gel method, for the first time. This paper also investigated the structures, spectral characters, luminescence behaviors, particles size and morphology of pure and doped SrZnO₂ phosphors by X-ray diffraction （XRD）, FT infrared, Raman spectrum, thermo-gravimetric analysis （TG）, ultraviolet and visible absorption spectrum, photoluminescence spectrum, and transmissions electron microscopy （TEM） respectively. The main conclusions are as follows:This as-prepared SrZnO₂ phosphor with white body-color contains little impurities phase and the SrZnO₂ phase is dominant. The SrZnO₂ phosphor particles are club-shaped with length of 500 nm and breadth of 30 nm. SrZnO₂ exhibits 545 nm green emission under the excitation of 380 nm. Luminescence properties of SrZnO₂ can be greatly affected by preparation conditions. When the sintering temperature, the ratio of citric acid to metal ions and the pH value of precursor solution is 1000℃, 3 : 1 and 5, respectively, it owns maximum emission intensity of photoluminescence. SrZnO₂ luminescent material is a promising green-emitting phosphor by long wavelength UV excitation because of its luminescence properties.The ultraviolet and visible absorption spectrum and photoluminescence spectrum prove that SrZnO₂ is a kind of new semiconductor material. Its green emission originates from the Vo in the SrZnO₂. The paper also studies the influence of Sr/Zn ratio on luminescence properties of SrZnO₂. When the ratio of Sr/Zn is 0.8:1, it owns maximum emission intensity of photoluminescence. Compared to the peak of SrZnO₂, when the SrO is excessive, the peak of sample is blue shifted, while the peak of sample is red shifted, when the ZnO is excessive.The photos of TEM show that the samples synthesized by citrate-gel method under different temperature have different shape. With the temperature increasing, the shapes became nano-cluster and changed to needled and stick, then returned to the nano-cluster.更多还原