Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin, China.
Dalton Trans. 2013 Jul 21;42(27):10019-28. doi: 10.1039/c3dt00029j. Epub 2013 May 28.
In this article, rare earth (RE) ion doped β-NaGdF4 crystals with multicolor up-conversion (UC) emissions and paramagnetic properties were synthesized via a simple one-step precipitation method at room-temperature for the first time. Different surfactants, including Na2EDTA, PVP, SDS, and Na2tar, were introduced to control the crystal size and morphology. It was found that the organic additive can strongly control the size and structure of as-prepared β-NaGdF4:Yb(3+),Ln(3+) samples through absorbing on the surface of primary particles and/or coordinating with RE(3+) ions. Most interestingly, the UC and magnetic properties of the NaGdF4 crystals were also greatly influenced by those additives, which exhibit great distinction. The red emission of (4)F(9/2)→(4)I(15/2) (655 nm) in β-NaGdF4:20%Yb(3+),2%Er(3+), (5)F5→(5)I8 (648 nm) in β-NaGdF4:20%Yb(3+),2%Ho(3+), and NIR emission of (3)H4→(3)H6 (797 nm) in β-NaGdF4:20%Yb(3+),2%Tm(3+) were all markedly enhanced due to abundant organic groups that affect the nonradiative processes. The magnetic properties of β-NaGdF4:Yb(3+),Er(3+) crystals prepared with different surfactants exhibit typical paramagnetic behavior with different intensities due to the different crystal shape anisotropy.
本文首次采用简单的室温一步沉淀法合成了具有多色上转换发射和顺磁性质的稀土（RE）离子掺杂的β-NaGdF4 晶体。不同的表面活性剂，包括 Na2EDTA、PVP、SDS 和 Na2tar，被引入以控制晶体的尺寸和形态。研究发现，有机添加剂可以通过在初级颗粒表面吸附和/或与 RE(3+)离子配位，强烈控制所制备的β-NaGdF4:Yb(3+),Ln(3+)样品的尺寸和结构。有趣的是，UC 和磁性能也受到这些添加剂的强烈影响，表现出很大的差异。β-NaGdF4:20%Yb(3+),2%Er(3+)中的(4)F(9/2)→(4)I(15/2)（655nm）红色发射，β-NaGdF4:20%Yb(3+),2%Ho(3+)中的(5)F5→(5)I8（648nm）和β-NaGdF4:20%Yb(3+),2%Tm(3+)中的 NIR 发射(3)H4→(3)H6（797nm）都由于丰富的有机基团影响非辐射过程而显著增强。由于不同的晶体形状各向异性，不同表面活性剂制备的β-NaGdF4:Yb(3+),Er(3+)晶体的磁性能表现出典型的顺磁行为，强度不同。
