【作者】 王伟华；

【导师】 吴红英； 德格吉呼；

【作者基本信息】 内蒙古师范大学 ， 无机化学， 2010， 硕士

【摘要】 稀土掺杂氟化物纳米材料具有优异的光学特性,在高清显示、固体激光器、防伪识别、红外探测、生物分析和医学诊断等诸多领域有着重要的应用前景,引起了人们的广泛关注。本文采用水热法,以CTAB、PEG、SDS为表面活性剂制备了不同形貌YF3:Yb3+/Er3+,LaF3:Yb3+/Tm3+,YF3:Yb3+/Tm3+上转换纳米晶体。探讨了纳米晶的制备工艺,并讨论了表面活性剂的浓度和pH值对形貌和粒径的调控能力。用X射线衍射分析、透射电子显微镜、扫描电子显微镜对样品进行物相、结构和形貌分析。XRD表征确认了样品YF3为斜方晶系,LaF3为六方晶系。SEM和TEM图片显示YF3:Yb3+/Er3+为簇状结构,LaF3:Yb3+/Tm3+为纳米片或纳米颗粒,YF3:Yb3+/Tm3+为纳米颗粒、微米管和微米棒。以978nm的半导体激光器为光源,用Hitachi F-4500分光光度仪测量样品的上转换发射光谱。YF3:Yb3+/Er3+棒状纳米簇具有很强的蓝色(4F5/2→4I15/2和2P3/2→4I11/2)和绿色(4S3/2,2H11/2→4I15/2)上转换发射光。LaF3:Yb3+/Tm3+纳米颗粒和纳米片可以观测到很强的紫外和蓝色上转换发射光。YF3:Yb3+/Tm3+微米管和微米棒有六个发射带:291nm、345nm、361nm、450nm、475nm和651nm。紫外发射带的中心在291nm、345nm、361nm处,与其对应的辐射跃迁分别是1I6→3H6、1I6→3F4、1D2→3H6。研究了泵浦功率与上转换发光强度的关系,通过相对光强与泵浦激发功率的双对数曲线,确定了样品的发射均为多光子过程。讨论了稀土离子的基态吸收、激发态吸收以及稀土离子之间能量传递的关系,建立了相关的上转换机制模型。更多还原

【Abstract】 For unique luminescence of the rare earth doped fluoride nanomaterials, these nanoparticles may find great applications in the fields of 3-D displays, bio-detection, solid-state lasers, anti-counterfeiting, infrared detection, and so on。The fluoride nanomaterials were synthesized by the sovlethermal method. The phase, stucture and morphology were analysised by X-ray diffraction, scansion electron microscopy (SEM), transmission electron microscopy (TEM). The XRD patterns were indexed to a pure YF3 orthorhombic phase and a pure LaF3 hexagonal phase. TEM and SEM images showed the morphology of YF3:Yb3+/Er3+, LaF3:Yb3+/Tm3+ and YF3:Yb3+/Tm3+, which were nanoclusters, nanosheets nanoparticles, microtubes, microrods.The ability of agent CTAB controlling the particle morphology and size were discussed.The upconversion spectrum was measured by Hitachi F-4600 spectrophotometer, under 978nm diode laser excitation. Stronger blue (4F5/2→4I15/2 and 2P3/2→4I11/2) and green (4S3/2, 2H11/2→4I15/2) upconversion emissions of Yb3+?Er3+ codoped YF3 rod-like nanoclusters were observed. The nanoparticles and nanosheets present strong ultraviolet and blue upconversion luminescence. There were six emission bands in the upconversion emission spectra of YF3:Yb3+/Tm3+, which peak at 291nm, 345nm, 361nm, 450nm, 475nm and 651nm. And they were corresponded to the 1I6→3H6, 1I6→3F4, 1D2→3H6 of Tm3+ cations.The relationship between upconversion relative intensity and pump power was also studied. Ground state absorption, excitation state absorption and energy transfer were used in discussing the upconversion mechanism of the nanocrystals and the pertinent upconversion mechanism models of the nanocrystals were proposed.更多还原