Dipartimento di Chimica and Centro di Eccellenza Materiali Innovativi Nanostrutturati (CEMIN), Università di Perugia, Via Elce di Sotto, 8, 06123 Perugia, Italy.
Inorg Chem. 2012 Dec 17;51(24):13229-36. doi: 10.1021/ic301584g. Epub 2012 Nov 27.
Nanosized Layered Double Hydroxides (LDH) were prepared in confined environment through the microemulsion method in the presence of different lanthanide cations (Ln(III) = Eu(III), Yb(III), Tb(III), and Nd(III)). To investigate the effects of lanthanide insertion in the sheets of LDH materials, several samples were prepared upon progressively increasing the content of Ln ions and properly reducing the Al(III) amount; the samples were characterized in terms of metal content, structure, morphology, thermal behavior, and spectroscopic properties. The data revealed that Ln(III) content in the LDH samples depends on the ionic radius of the lanthanide cations and on its concentration in the starting microemulsion. X-ray powder diffraction (XRPD) indicated that Eu(III) can be inserted into the LDH structure in average atomic percentages lower than 2.7%, leading to the formation of a low symmetry phase, as confirmed by steady state luminescence spectra; while Yb(III) can be incorporated into the layer structure up to about 10% forming a pure layered phase containing the lanthanide in the sheet. The incorporation of Yb(III) and Eu(III) into the LDH sheets is also supported by FT-IR measurements. Coupled thermogravimetrical (TG) and differential scanning calorimetric (DSC) studies indicated that water molecules are essential in the coordination sphere of incorporated Ln cations; this observation accounts for the lower thermal stability of Ln-doped LDH compared to the undoped ones. Furthermore, Eu-luminescence measurements indicates that the lanthanide inclusion does not compromise its luminescence although the spectral position and brightness can be tuned by the loading.
纳米级层状双氢氧化物（LDH）在微乳液存在下通过微乳液法在受限环境中制备，存在不同的镧系阳离子（Ln（III）= Eu（III），Yb（III），Tb（III）和 Nd（III））。为了研究镧系元素插入 LDH 材料层中的影响，通过逐渐增加Ln 离子的含量并适当减少 Al（III）的量来制备几种样品；通过金属含量，结构，形态，热行为和光谱特性对样品进行了表征。数据表明，LDH 样品中的 Ln（III）含量取决于镧系阳离子的离子半径及其在起始微乳液中的浓度。X 射线粉末衍射（XRPD）表明，Eu（III）可以以低于 2.7％的平均原子百分比插入 LDH 结构中，形成低对称相，这通过稳态发光光谱得到证实；而 Yb（III）可以掺入层状结构中，最高可达约 10％，形成纯层状相，层中包含镧系元素。FT-IR 测量也支持 Yb（III）和 Eu（III）掺入 LDH 层中。耦合热重（TG）和差示扫描量热法（DSC）研究表明，水分子是掺入的Ln 阳离子配位球中的必需物质；这一观察结果表明，与未掺杂的 LDH 相比，掺杂 Ln 的 LDH 的热稳定性较低。此外，Eu 发光测量表明，尽管可以通过负载来调整光谱位置和亮度，但镧系元素的掺入不会影响其发光。
