ScF_3,NaScF_4,(NH_4)_2NaScF_6的可控合成与上转换发光性能的研究

The Controllable Synthesis and Luminescent Properties of ScF_3,NaScF_4,(NH_4)_2NaScF_6 Nanaocrysals

钪基氟化物化学性质稳定、声子能量低、无辐射弛豫概率较低,是一种新型高效的基质材料,并且Sc^(3+)半径较小,能与多种氨羧络合剂形成稳定的螯合物,因而具有更加奇特的物理和化学性质,近年来,成为许多科学家研究的热点。以聚乙烯二胺(PEI)作为表面活性剂,采用水热法在反应温度为200℃时成功制备了ScF_3∶Yb^(3+)/Er^(3+),NaScF_4∶Yb^(3+)/Er^(3+),(NH_4)_2NaScF_6∶Yb^(3+)/Er^(3+)纳米上转换发光材料。通过X射线衍射仪(XRD)、透射电镜(TEM)、扫描电镜(SEM)和荧光光谱仪对所制备样品的晶相、形貌和发光特性进行了研究,结果显示:通过改变反应物NH_4F和Ln^(3+)的比例(NH_4F/Ln^(3+)=1∶1,2∶1,2.5∶1,3∶1,4∶1,6∶1,10∶1,20∶1,30∶1,40∶1,50∶1)实现了对样品产物、晶相、形貌的控制。当NH_4F/Ln^(3+)为2.5∶1时,生成了纯立方相的ScF_3;在NH_4F/Ln^(3+)为4∶1时,生成了六角相的NaScF_4;在NH_4F/Ln^(3+)为40∶1时,生成了一种纯立方相的新型基质材料(NH_4)_2NaScF_6,样品结晶度高,形貌均一,有正方形片状和足球状多面体;在980nm红外激光的激发下,不同NH_4F/Ln^(3+)比例生成的样品发光呈现桔黄→桔红→绿→黄绿等多种颜色的变化。实验表明仅改变NH_4F一种原料的用量,就可以生成ScF_3∶Yb^(3+)/Er^(3+),NaScF_4∶Yb^(3+)/Er^(3+)和(NH_4)_2NaScF_6∶Yb^(3+)/Er^(3+)三种不同的产物,说明NH_4F的用量对产物的生成有决定性的作用,对晶相的转换、颜色的调控亦有重要影响。

Scandium fluoride possess chemical stability,with low phonon energy and low potential cytotoxicity,is a new type of high efficient based material,and also distance between Sc3＋-Sc3＋ions is also lower.Thus it has more peculiar physical and chemical properties,recently.Recently,Scandium fluoride codoped with Yb3＋/Er3＋have attracted significant interest and become study hot fields.In the paper,using Polyetherimide（PEI）as surfactant,a series ScF3∶Yb3＋/Er3＋,NaScF4∶Yb3＋/Er3＋,（NH4）2NaScF6∶Yb3＋/Er3＋nanocrystals were prepared at 200℃by a facile hydrothermal method.By X-ray diffraction（XRD）,Transmission electron microscopy（TEM）,Scanning electron microscope（SEM）and fluorescence spectrometer,the crystal phase,morphology and luminescent characteristics of prepared samples were investigated.The results showed that the product,phase and morphology of sample can be tailored through varying the ratio of NH4F/Ln3＋（NH4F/Ln3＋=1∶1,2∶1,2.5∶1,3∶1,4∶1,6∶1,10∶1,20∶1,30∶1,40∶1,50∶1）.When the NH4F/Ln3＋ratio were 2.5∶1,the pure cubic phase ScF（3 ）was obtained.When NH4F∶Ln3＋ratio was 4∶1,the hexagonal phases NaScF（4 ）was obtained.When the NH4F∶Ln3＋ratio was 40∶1,the products were changed to pure cubic phase（NH4）2NaScF6.The TEM and the SEM showed that the crystallinity of samples was high and the particle size was uniform.The morphology were square nano piece and polyhedron of football shape in different ratio of NH4F/Ln3＋.Meanwhile,the UC fluorescence emission spectra were measured.The color of UC emission were tuned from orange to red,green and yellow in samples by adjusting the ratio of NH4F/Ln3＋.It turned out that just change NH4F one raw materials dosage,can generate ScF3∶Yb3＋/Er3＋,NaScF4∶Yb3＋/Er3＋,（NH4）2NaScF6∶Yb3＋/Er3＋three different kinds of products,which illustrate that NH4F dosage has decisive effect to the type of products.The UC emission intensity and out colour can be also significantly influenced by the ratio of NH4F/Ln3＋.