【作者】 张平；

【导师】 徐明霞；

【作者基本信息】 天津大学 ， 材料学， 2007， 博士

【摘要】 本文意旨研制开发一类不含放射性物质,具有优良发光特性的新型红色铝酸锶系长余辉发光材料。本论文用溶胶-凝胶法首次合成了新型花状形貌的Sr₃Al₂O₆:Eu²⁺, Dy³⁺红色长余辉发光粉体。详细研究了Sr₃Al₂O₆: Eu²⁺, Dy³⁺发光粉体的合成、颗粒微观形貌、光谱特性、发光机理以及余辉衰减过程等问题。系统地探讨了制备工艺、稀土离子浓度和杂质离子浓度等对发光粉体的结构和发光性能的影响。探明了发光粉体的最佳烧成温度为1200℃,最适宜的保温时间为2h。制得的花状形貌的Sr₃Al₂O₆:Eu²⁺, Dy³⁺发光粉体,在472nm激发下,发射峰值波长为612nm的红色宽带发射谱,余辉时间长达25min;研究发现Eu²⁺离子浓度达到8mol%时,发光强度达到最大,之后随着Eu²⁺离子浓度的继续增加,发生浓度猝灭;热释光谱和余辉衰减的测试结果证实了Dy³⁺离子的掺杂对发光体中的陷阱能级深度影响显著,进而影响其余辉特性。随着Dy³⁺离子浓度的增大,发光材料中的陷阱能级深度增加,但发光强度却下降,最佳Dy³⁺离子掺杂浓度为15mol%;杂质S2-离子的最佳添加量为0.4mol,可使余辉时间延长到45min。本论文还采用了节能高效的凝胶-微波加热法首次快速合成了红色Sr₃Al₂O₆: Eu²⁺, Dy³⁺和绿色SrAl2O4: Eu²⁺,Dy³⁺长余辉发光粉体。研究了微波功率和合成时间对发光粉体结构、形貌和发光性能的影响,确定了最佳微波功率为680W,合成时间分别为20min和15min。研究了掺杂Eu²⁺的铝酸锶系发光体中,Sr²⁺离子的配位环境、格位状态及其分布,确认了在发光体中Eu²⁺,Dy³⁺离子是取代Sr²⁺离子进入晶格,其发光颜色是由Eu²⁺离子的4f65d1→4f7（8S7/2）跃迁所决定的。提出了一种运用光谱拟合分峰处理来表征、确定掺Eu²⁺的铝酸锶系发光体中晶场对Eu²⁺的5d能级劈裂强度影响的方法,依此确定了分别属立方和单斜晶系的Sr₃Al₂O₆:Eu²⁺发光体和SrAl2O4:Eu²⁺发光体中Eu²⁺的4f-5d发射带因晶场作用引起的5d能级劈裂幅度分别为91nm和56nm。合成了新型晶体形貌的Sr₃Al₂O₆: Eu²⁺发光粉体,对Sr₃Al₂O₆纳米晶体自组装生长机理进行了探讨,确定了Sr₃Al₂O₆花状晶体是由纳米晶须和纳米棒自组装生长而成的。研究了Sr₃Al₂O₆:Eu²⁺发光粉体的新型微观结构和形貌对发光性能的影响,均匀分散的花状形貌Sr₃Al₂O₆:Eu²⁺发光粉体对于提高发光强度和余辉时间非常有利。更多还原

【Abstract】 Research on the strontium aluminate phosphors doped with Eu²⁺ is made to develop new high-efficient, long-persistent and red phosphors without radioactive substance.In this paper, new flower-like Sr₃Al₂O₆: Eu²⁺, Dy³⁺ red phosphor powders were prepared by a sol-gel method in the reducing atmosphere. The synthesis, particle morphology, spectrum properties, luminescence mechanism and afterglow characteristics of Sr₃Al₂O₆: Eu²⁺, Dy³⁺ phosphors were detailed investigated. And the effects of preparation conditions, the concentration of rare earth ions and additive ions on the microstructure and luminescent properties of phosphors were systematically discussed. It is discovered that optimal temperature and time of calcining are 1200oC and 2h, respectively. The flower-like Sr₃Al₂O₆: Eu²⁺ phosphor powders exhibited a red abroad emission band with emission peak at 612nm under the excitation of 472nm and afterglow lased for more than 25min. It is discovered that the emission intensity of phosphors increased firstly then decreased with the concentration of Eu²⁺ ions and reaches its highest intensity at 8mol%. Based on the research on the thermoluminescence spectra and fluorescent decay, Dy³⁺ plays an important role in the system resulted in different decay time. With the concentration of Dy³⁺ increasing, the depth of trapping energy levels in the phosphor increases, but the emission intensity decreases. The optimal concentration of Dy³⁺ is 15mol%. The optimal content of S2- is 0.4mol and afterglow lased for 45min.Red Sr₃Al₂O₆: Eu²⁺, Dy³⁺ and green SrAl2O4: Eu²⁺, Dy³⁺ phosphor powders were firstly prepared by gel-microwave heating method in the reducing atmosphere. The effects of microwave power and heating time on the microstructure, particle morphology and luminescent properties of phosphors were discussed. It is discovered that optimal microwave power is 680W and heating times are 20min and 15min, respectively.The coordinate environment and site distribution of Sr²⁺ ions in the strontium aluminate phosphors activated by Eu²⁺ were investigated. It is determined that Eu²⁺ replaces for Sr²⁺ and the emitting fluorescence color is determined by the 4f65d1→4f7 transfer of Eu²⁺. A new method is firstly brought out for determining the influence of crystal field on 5d level of Eu²⁺. According to this method, the splitting of 5d of Eu²⁺ in Sr₃Al₂O₆: Eu²⁺ and SrAl2O4:Eu²⁺ are determined as 91nm and 56nm respectively. New morphology Sr₃Al₂O₆: Eu²⁺ phosphor powders were synthesized. The self-assembled formation mechanism is discussed. It is proved that flower-like Sr₃Al₂O₆ are assembled by nanowhiskers and nanorod. And the effects of new microstructure and morphology on luminescent properties of phosphors were investigated. Uniformity dispersive flower-like Sr₃Al₂O₆:Eu²⁺ phosphor powders showed the strongest luminescent intensity, and longest afterglow time.更多还原