Kostova Mariya H, Ananias Duarte, Paz Filipe A Almeida, Ferreira Artur, Rocha João, Carlos Luís D
Departments of Chemistry and Physics and ESTGA, CICECO, University of Aveiro, 3810-193 Aveiro, Portugal.
J Phys Chem B. 2007 Apr 12;111(14):3576-82. doi: 10.1021/jp068559u. Epub 2007 Mar 22.
The dehydratation process of layered lanthanide silicates K3[LnSi3O8(OH)2], Ln = Y, Eu, Tb, and Er, and the structural characterization of the obtained small-pore framework K3LnSi3O9, Ln = Y, Eu, Tb, and Er solids, named AV-23, have been reported. The structure of AV-23 has been solved by single-crystal X-ray diffraction (XRD) methods and further characterized by chemical analysis, thermogravimetry, scanning electron microscopy, and 29Si MAS NMR. The photoluminescence (PL), radiance, and lifetime values of AV-23 have been studied and compared with those of AV-22. Both materials have a similar chemical makeup and structures sharing analogous building blocks, hence providing a unique opportunity for rationalizing the evolution of the PL properties of lanthanide silicates across dimensionality. Although Tb-AV-23 contains a single crystallographic Tb(3+) site, PL spectroscopy indicates the presence of Ln(3+) centers in regular framework positions and in defect regions. PL evidence suggests that Eu-AV-23 contains a third type of Ln(3+) environment, namely, Eu(3+) ions replacing K(+) ions in the micropores. The radiance values of the Tb-AV-22 and Tb-AV-23 samples are of the same order of magnitude as those of standard Tb(3+) green phosphors. For the samples K3(Y1-aEraSi3O9), a = 0.005-1, efficient emission and larger 4I13/2 lifetimes (ca. 7 ms) are detected for low Er(3+) content, indicating that the Er(3+)-Er(3+) interactions become significant as the Er(3)+ content increases.
已报道了层状镧系硅酸盐K3[LnSi3O8(OH)2]（Ln = Y、Eu、Tb和Er）的脱水过程以及所得小孔框架K3LnSi3O9（Ln = Y、Eu、Tb和Er）固体（命名为AV - 23）的结构表征。AV - 23的结构已通过单晶X射线衍射（XRD）方法解析，并通过化学分析、热重分析、扫描电子显微镜和29Si MAS NMR进一步表征。研究了AV - 23的光致发光（PL）、辐射率和寿命值，并与AV - 22的进行了比较。两种材料具有相似的化学组成和结构，共享类似的结构单元，因此为合理化镧系硅酸盐PL性质在不同维度上的演变提供了独特的机会。尽管Tb - AV - 23包含单个晶体学Tb(3+)位点，但PL光谱表明在规则框架位置和缺陷区域存在Ln(3+)中心。PL证据表明Eu - AV - 23包含第三种类型的Ln(3+)环境，即Eu(3+)离子在微孔中取代K(+)离子。Tb - AV - 22和Tb - AV - 23样品的辐射率值与标准Tb(3+)绿色磷光体的辐射率值处于同一数量级。对于样品K3(Y1 - aEraSi3O9)，a = 0.005 - 1，在低Er(3+)含量时检测到高效发射和更长的4I13/2寿命（约7 ms），表明随着Er(3+)含量增加，Er(3+) - Er(3+)相互作用变得显著。
