稀土锆酸盐体系荧光粉的制备及发光性能研究

发布时间：2018-08-27 17:41

【摘要】：稀土离子特殊的4f电子在f-f组态之内及f-d组态之间的跃迁发射,可产生大量的辐射和荧光光谱信息。它们可以发射各类从紫外光、可见光到红外光区多种波长的电磁辐射。其发光特点具有:亮度高、色彩鲜艳、色纯度高、光吸收能力强、发射波长可调等优点。所以近几年来,稀土无机发光材料已成为照明、显示、光通讯及医学影像等诸多显示领域的支柱材料,研发制备高性能荧光粉已经成为新时期发光材料领域的重要课题。鉴于此,根据稀土材料的理化性质,本论文拟研究以锆酸盐为基质的稀土发光材料,通过水热法分别制备了Gd_2Zr_2O_7、Y_2Zr_2O_7荧光粉,掺杂激活离子(Eu~(3+),Tb~(3+))实现红、绿光发射,并讨论不同表面活性剂在改善荧光粉发光性能方面的作用。得到的主要结论如下:1.采用水热法制备了Gd_2Zr_2O_7:Eu~(3+)红色荧光粉,探索Eu~(3+)的最优掺杂比例。采用X射线衍射仪(XRD)、扫描电镜(FE-SEM)、荧光光谱(PL)等表征手段对荧光粉的物相组成、微观结构和发光性能进行分析。XRD谱图分析表明不同Eu~(3+)掺杂浓度样品(Gd1-xEux)_2Zr_2O_7的衍射峰基本一致,与标准物相卡片Gd_2Zr_2O_7(JCPDS no.16-0799)相吻合并证实样品的微观结构为有序的烧绿石结构。由FE-SEM观察可知样品的微观结构为纳米棒,长度约为2000-3000 nm,直径在300 nm左右。PL分析表明,当Eu~(3+)掺杂浓度达到4%时,样品在613 nm(5D0→7F2)处的发光强度达到最大值,继续掺杂强度反而下降,出现了浓度猝灭现象。文章着重对其发光机理、影响发光性能的因素给予解释并提出进一步优化性能的方案;2.采用水热法制备Gd_2Zr_2O_7:Tb~(3+)绿色荧光粉,通过XRD、FE-SEM、TEM、PL等表征手段对实验结果进行分析。结果显示,Gd_2Zr_2O_7:Tb~(3+)荧光粉的微观一维纳米棒直径约为30 nm,长度在150-300 nm范围内。PL测试结果表明,Tb~(3+)展现出了较强的绿光发射性能,归属于Tb~(3+)的5D4→7FJ(J=3-6)的电子跃迁发射,最强发射峰出现在545 nm(5D4→7F5)处,当Tb~(3+)掺杂浓度为5%时出现了明显的浓度猝灭,探讨了Tb~(3+)之间的交叉驰豫对发光强度及光纯度的影响。本节采用高温固相法制备的对比样品(Gd0.95Tb0.05)_2Zr_2O_7的微观形貌为不规则的多边形,尺寸不均匀,发光强度略高于水热法。3.以Y_2Zr_2O_7为基质材料,采用水热法制备Y_2Zr_2O_7:Tb~(3+)绿色荧光粉。荧光光谱分析表明,(Y1-x Tbx)2ZrO7荧光粉的最强发射峰归属于Tb~(3+)的5D4→7F5电子跃迁(545 nm)的强绿光发射,通过公式计算出发生浓度猝灭时Tb~(3+)之间的距离并证实此时交叉驰豫是影响浓度猝灭的主要原因。FE-SEM证实,所制备的产物为空心纳米管状结构,内直径约为80~130nm,管壁厚度在30~70 nm范围之间,长度在3~5μm之间,这种形貌规则性高、分散性好的纳米级荧光粉具有较好的应用前景;4.在已知Y_2Zr_2O_7:Tb~(3+)荧光粉中Tb~(3+)的最优掺杂比例的前提下,依次添加有机添加剂十二烷基苯磺酸钠(SDBS)、十二烷基硫酸钠(SDS)、非离子表面活性剂聚乙烯吡咯酮(PVP)、有机盐类乙二胺四乙酸二钠(EDTA)四种表面活性剂来提高荧光粉的发光强度。添加四种表面活性剂样品的微观颗粒为纳米棒结构。通过与无添加样品对比可知,表面活性剂可明显提高荧光粉的光吸收能力、量子效率、发光强度,其中掺杂有EDTA的荧光粉其发光强度是无表面活性剂添加样品的7倍,同时其微观纳米棒尺寸均匀、表面光滑,形貌规则性良好,具备高性能荧光粉的应用潜力。
[Abstract]:The special 4f electrons of rare earth ions emit a great deal of radiation and fluorescence information in the f-f configuration and between the F-D configuration. They can emit electromagnetic radiation of various wavelengths from ultraviolet, visible to infrared regions. Their luminescence characteristics are high brightness, bright color, high color purity, strong light absorption ability and emission. In recent years, rare earth inorganic luminescent materials have become the backbone materials for illumination, display, optical communication, medical imaging and many other display fields, and the development and preparation of high-performance phosphors have become an important issue in the field of luminescent materials in the new era. Gd_2Zr_2O_7, Y_2Zr_2O_7 phosphors were synthesized by hydrothermal method with zirconate as the base material. Red and green light emission was achieved by doping active ions (Eu~ (3+), Tb~ (3+). The effects of different surfactants on improving the luminescent properties of phosphors were discussed. The main conclusions were as follows: 1. Gd_2Zr_2O_7 phosphors were prepared by hydrothermal method. X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), fluorescence spectroscopy (PL) and other characterization methods were used to analyze the phase composition, microstructure and luminescent properties of Eu~ (3+) red phosphors. XRD spectra showed that the diffraction peaks of samples with different Eu~ (3+) doping concentrations (Gd1-xEux) _2Zr_2O_7 were basically the same. The microstructure of the sample was confirmed to be ordered pyrochlore structure. The FE-SEM observation showed that the microstructure of the sample was nanorods with a length of about 2000-3000 nm and a diameter of about 300 nm. PL analysis showed that when Eu~ (3+) doping concentration reached 4%, the sample was 613 nm (5D0-7F). 2) The luminescent intensity reaches the maximum value, but the doping intensity decreases and the concentration quenching occurs. The luminescent mechanism and the factors affecting the luminescent properties are explained and a scheme for further optimizing the luminescent properties is proposed. 2. Gd_2Zr_2O_7:Tb~ (3+) green phosphor is prepared by hydrothermal method and characterized by XRD, FE-SEM, TEM and PL. The results show that the diameter of Gd_2Zr_2O_7:Tb~ (3+) nanorods is about 30 nm and the length is in the range of 150-300 nm. The PL test results show that Tb~ (3+) exhibits a strong green emission property, belonging to the 5D4 7FJ (J = 3-6) of Tb~ (3+) and the strongest emission peak appears at 545 nm. At 5D4 7F5, the concentration quenching of Tb ~ (3 +) doping occurs when the concentration of Tb ~ (3 +) is 5%. The effect of cross-relaxation between Tb ~ (3 +) on the luminous intensity and optical purity is discussed. In this section, the contrast sample (Gd0.95Tb0.05) _2Zr_2O_7 prepared by high temperature solid-phase method is an irregular polygon with uneven size and slightly higher luminous intensity. 3. Y_2Zr_2O_7:Tb~ (3+) green phosphor was prepared by hydrothermal method using Y_2Zr_2O_7 as the substrate material. The fluorescence spectrum analysis showed that the strongest emission peak of the (Y1-x Tb x) 2ZrO_7 phosphor belonged to the strong green emission of the 5D4 7F5 electron transition (545 nm) of Tb~ (3+) when the concentration quenching occurred. The distance between Tb~ (3+) was calculated by formula. FE-SEM confirmed that the product was a hollow nanotube with an inner diameter of 80-130 nm, a wall thickness of 30-70 nm and a length of 3-5 micron. This kind of phosphor with high regularity of morphology and good dispersion has a good application prospect. On the premise of optimum doping ratio of Tb~ (3 +) in Y_2Zr_2O_7:Tb~ (3 +) phosphor, four surfactants, sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), non-ionic surfactant polyvinylpyrrolidone (PVP), organic salt disodium ethylenediaminetetraacetate (EDTA), were added to improve the luminescence intensity of phosphor. The results show that the surface active agent can obviously improve the light absorption ability, quantum efficiency and luminous intensity of phosphors. The luminous intensity of the phosphors doped with EDTA is 7 times higher than that of the samples without surfactant, and the micro-nano-scale of the phosphors is also obtained. The rice bar is uniform in size, smooth in surface and regular in shape. It has the potential of high performance phosphor.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ422

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