Polarized Luminescence of Anisotropic LaPO4:Eu Nanocrystal Polymorphs
Polarized Luminescence of Anisotropic LaPO4:Eu Nanocrystal Polymorphs
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DOI：
10.1021/jacs.8b03983
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发表时间：
2018-08-01
影响因子：
15
通讯作者：
Gacoin, Thierry
中科院分区：
文献类型：
--
作者：
Chaudan, Elodie;Kim, Jongwook;Gacoin, Thierry
镧系元素表现出非常吸引人的光谱特性，广泛用于荧光粉应用。它们的发光包含了宿主材料内部结构的精确信息。特别是，过渡亚能级峰的极化行为是晶体相、对称性和缺陷的指纹。然而，在目前对镧系纳米磷光体的研究中，对这一独特特性的探索很少。本文报道了在LaPO4纳米晶主体热诱导相变过程中Eu3+发光的演化过程。通过c轴排列的纳米晶组件，我们证明了不同的LaPO4多晶中不同的Eu3+位对称性对应的发射极化特征的巨大变化。我们还表明，这种光谱方法可以识别纳米晶体结构的变化，其灵敏度远高于x射线衍射分析。这种对纳米结构-发光关系的新认识，以及前所未有的极化表征，为研究纳米材料的相变提供了一种新的方法。它还提出了镧系元素发射器作为取向传感纳米探针的新功能，可用于生物成像或微流体等创新应用。
Lanthanide elements exhibit highly appealing spectroscopic properties that are extensively used for phosphor applications. Their luminescence contains precise information on the internal structure of the host materials. Especially, the polarization behavior of the transition sublevel peaks is a fingerprint of the crystal phase, symmetry, and defects. However, this unique feature is poorly explored in current research on lanthanide nanophosphors. We here report on a detailed investigation of the evolution of Eu3+ luminescence during the thermally induced phase transition of LaPO4 nanocrystal hosts. By means of c-axis-aligned nanocrystal assemblies, we demonstrate a dramatic change of the emission polarization feature corresponding to the distinct Eu3+ site symmetries in different LaPO4 polymorphs. We also show that changes of the nanocrystal structure can be identified by this spectroscopic method, with a much higher sensitivity than the X-ray diffraction analysis. This new insight into the nanostructure-luminescence relationship, associated with the unprecedented polarization characterizations, provides a new methodology to investigate phase transitions in nanomaterials. It also suggests a novel function of lanthanide emitters as orientation-sensing nanoprobes for innovative applications such as in bioimaging or microfluidics.