Energy transfer between rare earths in layered rare-earth hydroxides (LRHs) is worth the intensive study because the hydroxyls that act as the bridge connecting the neighbouring rare earths would generate non-radiative transitions. This study focuses on the energy transfer in the intralayer and the adjacent layers of LRHs. A series of LEu_xTb_1−xHs (x = 0, 0.05, 0.2, 0.5, 0.8, and 0.95) was synthesized, the basal spacing (d_basal) was adjusted from 8.3 to 46 Å through ion-exchange process, and unilamellar nanosheets were prepared through a delamination process. The luminescence behaviours of the samples demonstrated the following: (1) for the delaminated nanosheets, the quenching effect of both Eu³⁺ and Tb³⁺ was hardly observed. This implies that in the intralayer, the efficiency of energy transfer is extremely low, so that highly-concentrated co-doping does not influence the luminescence and by controlling the Eu/Tb molar ratio, white light can be obtained. (2) For small d_basal, e.g., 27 Å, the fluorescence quenching of Tb³⁺ and Eu³⁺ was remarkable, while for large d_basal, e.g., 46 Å, the emission of Tb³⁺ emerged and the self-quenching between Eu³⁺ ions weakened. (3) The energy transfer efficiency deceased with an increase in the distance between adjacent layers. In other words, either the energy transfer between Eu³⁺ and Tb³⁺ or the energy migration between Eu³⁺ ions was more efficient when they were located in adjacent layers than in intralayers even when they were the nearest neighbours.

中文翻译：

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层状稀土氢氧化物中稀土之间的能量转移†

层状稀土氢氧化物 (LRH) 中稀土之间的能量转移值得深入研究，因为充当连接相邻稀土的桥梁的羟基会产生非辐射跃迁。本研究侧重于 LRH 层内和相邻层中的能量转移。合成了一系列 LEu _x Tb _{1− x} Hs ( x = 0, 0.05, 0.2, 0.5, 0.8, 和 0.95)，通过离子交换过程将基底间距 ( d _basal ) 从 8.3 调整到 46 Å，并且通过分层工艺制备单层纳米片。样品的发光行为表明：（1）对于分层的纳米片，两种Eu的猝灭效应几乎没有观察到³⁺和Tb ^{3+ 。}这意味着在层内，能量转移效率极低，因此高浓度共掺杂不会影响发光，通过控制 Eu/Tb 摩尔比，可以获得白光。(2) 对于小的d _basal，例如27 Å，Tb ³⁺和Eu ³⁺的荧光猝灭显着，而对于大d _basal，例如，46 Å，Tb ³⁺的发射和自猝灭出现Eu ^3+之间离子减弱。(3) 能量传递效率随着相邻层间距的增加而降低。换言之，Eu ³⁺和Tb ^{3+之间的能量转移或Eu 3+}离子之间的能量迁移在它们位于相邻层时比在层内更有效，即使它们是最近的邻居。