The up-conversion NaGdF4: Yb3 + , Ho3 + and GdF3: Yb3 + , Ho3 + nanocrystals were successfully prepared by hydrothermal method. The samples were characterized by X-ray powder diffraction (XRD) , scanning electron microscopy ( SEM) and luminescence spectra. The crystal structure and morphology can be well controlled by adjusting the molar ratio of re ( F-): n(Ln3+) ,the value of pH and the molar ratio of re( Citrate) : n(Ln). The hexagonal NaGdF4: Yb3+ ,Ho3+ and GdF3= Yb3+ ,Ho3 + samples exhibit green(541 nm)and red (647 nm) emissions under 980 nm excitation, which are assigned to the transition of 5F4,5S2→5I8 and 5F5→5I8 in Ho3+ , respectively. It was found that the upconversion efficiency of the hexagonal prism and flake NaGdF4: Yb3+ ,Ho3+ samples are much stronger than that of GdF3: Yb3 + , Ho3 + samples, but the spherical NaGdF4: Yb3+ ,Ho3+ samples are weaker than GdF3 = Yb3+ ,Ho3+ samples. This indicates that the upconversion efficiency of hexagonal NaGdF4: Yb3 + , Ho3+ samples are greatly impacted by the different size and crystalline for different morphology.%采用水热法通过调控n(F-):n(Ln3+),pH值以及n(Citrate):n(Ln)等一系列反应条件,合成了六方相的NaGdF4:Yb3,ho3+与GdF3:yb3+,Ho3+纳米上转换材料,实现了形貌的可控合成.利用X射线粉末衍射(XRD),场扫描电子显微镜(SEM)以及发光光谱等手段对产物的物相结构、形貌和荧光性质进行了研究.在980 nm光激发下,六方相的NaGdF4:Yb3+,Ho3与GdF3:Yb3+,Ho3+样品均显示出绿光(541 nm)和红光(647 nm)发射,分别来自于Ho3+的5 F4,5S2→5I8和5F5→5I8的跃迁.结果显示NaGdF4:Yb3+,Ho3+六棱柱与六棱片结构的发光远强于GdF3:Yb3+,Ho3+的发光,但在pH =7.0,9.0时生成的NaGdF4:yb3+,Ho3球形结构发光效率低于GdF3:Yb3+,Ho3+.这表明六方相NaGdF4:Yb3+,Ho3+不同形貌样品的尺寸与结晶性对发光效率影响很大.
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