Dong Guoping, He Huilin, Pan Qiwen, Chen Gengxu, Xie Junhua, Ma Zhijun, Peng Mingying
State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510640 (P. R. China).
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (P. R. China).
Chempluschem. 2014 Apr;79(4):601-609. doi: 10.1002/cplu.201300373. Epub 2014 Feb 24.
Yb /Tm -codoped NaYF nanocrystals with different phases (cubic α and hexagonal β) and morphologies (nanoparticles, nanorods, nanoplates) have been controllably fabricated by a convenient hydrothermal synthesis technique. Up-conversion emission peaks were observed at λ=450, 475, 645, and 700 nm, which were assigned to the D - F , G - H , G - F , and F - H transitions of Tm ions, respectively. By using a homemade detection system, the anisotropic polarized emission properties of individual NaYF :Yb, Tm nanorods and nanoplates were investigated. The results indicated that the polarization emission ratio, ρ, of the G - F emission of individual NaYF :Yb,Tm nanorods was 0.18, whereas the anisotropic polarization emission of individual NaYF :Yb,Tm nanoplates could be neglected; this indicated that the size and morphology of the nanocrystal played an important role in the polarized emission properties. Investigation into the mechanism indicated that the dielectric mismatch was not the predominant mechanism for the polarized emission of individual NaYF :Yb,Tm nanorods. The as-prepared NaYF :Yb,Tm nanocrystals, with controllable morphology and anisotropic polarized emission properties, are expected to be widely applied as polarized light resources, bio-labels, photodetectors, and so forth.
通过一种简便的水热合成技术，可控地制备出了具有不同相（立方α相和六方β相）和形貌（纳米颗粒、纳米棒、纳米片）的Yb/Tm共掺杂NaYF纳米晶体。在λ = 450、475、645和700 nm处观察到了上转换发射峰，它们分别归属于Tm离子的(^{2}D_{3/2}\rightarrow^{2}F_{7/2})、(^{2}G_{4}\rightarrow^{2}H_{9/2})、(^{2}G_{4}\rightarrow^{2}F_{5/2})和(^{2}F_{5/2}\rightarrow^{2}H_{9/2})跃迁。利用自制的检测系统，研究了单个NaYF:Yb,Tm纳米棒和纳米片的各向异性偏振发射特性。结果表明，单个NaYF:Yb,Tm纳米棒的(^{2}G_{4}\rightarrow^{2}F_{5/2})发射的偏振发射比ρ为0.18，而单个NaYF:Yb,Tm纳米片的各向异性偏振发射可忽略不计；这表明纳米晶体的尺寸和形貌在偏振发射特性中起着重要作用。对其机理的研究表明，介电失配不是单个NaYF:Yb,Tm纳米棒偏振发射的主要机理。所制备的具有可控形貌和各向异性偏振发射特性的NaYF:Yb,Tm纳米晶体有望作为偏振光资源、生物标签、光电探测器等得到广泛应用。
