Evolution of Photoluminescence across Dimensionality in Lanthanide Silicates

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• 作者：Mariya H. Kostova ; Duarte Ananias ; Filipe A. Almeida Paz ; Artur Ferreira ; Joã ; o Rocha ; Luí ; s D. Carlos
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：April 12, 2007
• 年：2007
• 卷：111
• 期：14
• 页码：3576 - 3582
• 全文大小：394K
• 年卷期：v.111,no.14(April 12, 2007)
• ISSN：1520-5207

文摘

The dehydratation process of layered lanthanide silicates K₃[LnSi₃O₈(OH)₂], Ln = Y, Eu, Tb, and Er, andthe structural characterization of the obtained small-pore framework K₃LnSi₃O₉, Ln = Y, Eu, Tb, and Ersolids, named AV-23, have been reported. The structure of AV-23 has been solved by single-crystal X-raydiffraction (XRD) methods and further characterized by chemical analysis, thermogravimetry, scanning electronmicroscopy, and ²⁹Si MAS NMR. The photoluminescence (PL), radiance, and lifetime values of AV-23 havebeen studied and compared with those of AV-22. Both materials have a similar chemical makeup and structuressharing analogous building blocks, hence providing a unique opportunity for rationalizing the evolution ofthe PL properties of lanthanide silicates across dimensionality. Although Tb-AV-23 contains a singlecrystallographic Tb³⁺ site, PL spectroscopy indicates the presence of Ln³⁺ centers in regular framework positionsand in defect regions. PL evidence suggests that Eu-AV-23 contains a third type of Ln³⁺ environment, namely,Eu³⁺ ions replacing K⁺ ions in the micropores. The radiance values of the Tb-AV-22 and Tb-AV-23 samplesare of the same order of magnitude as those of standard Tb³⁺ green phosphors. For the samplesK₃(Y_1-aEr_aSi₃O₉), a = 0.005-1, efficient emission and larger ⁴I_13/2 lifetimes (ca. 7 ms) are detected for lowEr³⁺ content, indicating that the Er³⁺-Er³⁺ interactions become significant as the Er³⁺ content increases.