超细YF_3与GdF_3纳米晶的合成及其上转换发光

当使用液固溶法(LSS法)制备分散性纳米晶时,将传统油酸/油酸钠/酒精反应体系中的NaOH用氨水取代时,氨水将会与油酸形成新的表面活性剂油酸铵,这样就可以合成各种超细分散性的REF3纳米晶(RE代表稀土元素)。在这种新的反应体系中,合成了平均直径小于10 nm的YF3和GdF3超细颗粒,X射线与透射电镜测试表明YF3是正交相,而GdF3是面心立方结构,空间群为Fm3m,晶格常数为0.582 9 nm。在980 nm半导体激光器激发下,可检测到YF3∶Yb/Er在515~570 nm处有较强的绿色发光峰、645~675 nm处有较强的红色发光峰,呈橙色发光。YF3∶Yb/Tm和GdF3∶Yb/Tm样品在460~490 nm处有较强的蓝色发光峰,而在800 nm附近有更强的近红外发光峰。由于其超细的尺寸及红外上转换发光特性,合成的样品在生物成像、生物标签等方面有潜在的应用价值。

Synthesis and Upconversion Luminescence of Ultrasmall YF3 and GdF3 Nanocrystallines

In liquid-solid-solution (LSS) method, when NaOH in the traditional oleic acid/sodium oleate/alcohol reaction system was replaced by ammonia, ammonia reacted with oleic acid, and then a new kind surfactant generated. So, this method can be used to synthesize monodispersed ultrasmall REF₃ nanocrystals. In this new reaction system, ultrasmall YF₃ and GdF₃ nanocrystals have been synthesized. X-ray diffraction (XRD) and transmission electron microscopy (TEM) assays revealed that the as-synthesized YF₃ was orthorhombic structure, but GdF₃ was face-centered cubic phase (S. G.: Fm3m, lattice constant: 0.5829 nm). Under the excitation of 980 nm diode laser, strong green photoluminescence at 515~570 nm and strong red emission at 645~675 nm of YF₃:Yb/Er were detected, so the luminescent color of YF₃:Yb/Er nanocrystals presented orange. Intense blue emission peaks at 460~490 nm from YF₃:Yb/Tm and GdF₃:Yb/Tm nanocrystals were detected, especially the stronger near-infrared photoluminescence peaks near 800 nm. For the ultrasmall size and its relative strong upconversion luminescence, the as-synthesized samples show potential applications in bioimaging, biolabels and etc.