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首页> 外文期刊>Advanced Functional Materials >Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln~(3+)-Doped Gd_2O_3 Nanotubes
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Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln~(3+)-Doped Gd_2O_3 Nanotubes

机译：声子限制对掺Ln〜（3+）的Gd_2O_3纳米管异常热化，能量转移和上转换的影响

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摘要

There is a growing interest in understanding how size-dependent quantum confinement affects the photoluminescence efficiency, excited-state dynamics, energy-transfer and thermalization phenomena in nanophosphors. For lanthanide (Ln~(3+))-doped nanocrystals, despite the localized 4f states, confinement effects are induced mostly via electron-phonon interactions. In particular, the anomalous thermalization reported so far for a handful of Ln~(3+)-doped nanocrystals has been rationalized by the absence of low-frequency phonon modes. This nanoconfinement may further impact on the Ln~(3+) luminescence dynamics, such as phonon-assisted energy transfer or upconversion processes. Here, intriguing and unprecedented anomalous thermalization in Gd_2O_3:Eu~(3+) and Gd_2O_3:Yb~(3+),Er~(3+) nanotubes, exhibiting up to one order of magnitude larger than previously reported for similar materials, is reported. This anomalous thermalization induces unexpected energy transfer from Eu~(3+) C_2 to S_6 crystallographic sites, at 11 K, and ~2H_(11/2) → ~4I_(15/2) Er~(3+) upconversion emission; it is interpreted on the basis of the discretization of the phonon density of states, easily tuned by varying the annealing temperature (923-1123 K) in the synthesis procedure, and/or the Ln~(3+) concentration (0.16-6.60%).
机译：人们越来越了解理解尺寸依赖的量子限制如何影响纳米磷光体的光致发光效率，激发态动力学，能量转移和热化现象。对于掺杂镧系元素（Ln〜（3+））的纳米晶体，尽管存在局部4f态，但主要通过电子-声子相互作用诱导了约束效应。尤其是，迄今为止报道的少数掺Ln〜（3+）纳米晶体的异常热化因缺乏低频声子模式而得以合理化。这种纳米限制可能进一步影响Ln〜（3+）发光动力学，例如声子辅助的能量转移或上转换过程。在这里，Gd_2O_3：Eu〜（3+）和Gd_2O_3：Yb〜（3 +），Er〜（3+）纳米管中有趣且前所未有的异常热化是比以前报道的类似材料大一个数量级的。报告。这种异常的热化作用导致在11 K时从Eu〜（3+）C_2到S_6晶体学位置发生了意外的能量转移，并且〜2H_（11/2）→〜4I_（15/2）Er〜（3+）上转换发射；它的解释是基于状态声子密度的离散化，可以通过在合成过程中改变退火温度（923-1123 K）和/或Ln〜（3+）浓度（0.16-6.60％ ）。

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  • 来源
    《Advanced Functional Materials》 |2010年第4期|624-634|共11页
  • 作者

    Andreia G. Macedo; Rute A. S. Ferreira; Duarte Ananias; Mario S. Reis; Vitor S. Amaral; Luis D. Carlos; Joao Rocha;

  • 作者单位

    Department of Physics and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

    Department of Physics and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

    Department of Chemistry and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

    Department of Physics and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

    Department of Physics and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

    Department of Physics and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

    Department of Chemistry and CICECO Universidade de Aveiro 3810-193 Aveiro (Portugal);

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