Institute for Nuclear Waste Disposal, Karlsruhe Institute of Technology, Karlsruhe, Germany.
Dalton Trans. 2013 Jun 21;42(23):8387-93. doi: 10.1039/c3dt50146a. Epub 2013 Apr 24.
We present a comprehensive study of the solid solution system Ca2(MoO4)2-NaGd(MoO4)2 on the molecular scale, by means of site-selective time resolved laser fluorescence spectroscopy (TRLFS). Eu(3+) is used as a trace fluorescent probe, homogeneously substituting for Gd(3+) in the solid solution crystal structure. Site-selective TRLFS of a series of polycrystalline samples covering the whole composition range of the solid solution series from 10% substitution of Ca(2+) to the NaGd end-member reveals it to be homogeneous throughout the whole range. The trivalent ions are incorporated into the powellite structure in only one coordination environment, which exhibits a very strong ligand-metal interaction. Polarization-dependent measurements of a single crystal of NaGd(Eu)(MoO4)2 identify the coordination geometry to be of C2v point symmetry. The S4 symmetry of the Ca site within the powellite lattice can be transformed into C2v assuming minor motion in the first coordination sphere.
我们通过分子尺度的选择点时分辨激光荧光光谱（TRLFS）对 Ca2（MoO4）2-NaGd（MoO4）2 固溶体系进行了全面的研究。Eu（3+）被用作荧光探针，均匀取代固溶晶体结构中的 Gd（3+）。对一系列多晶样品的选择点 TRLFS 测量，涵盖了固溶系列从 10% Ca（2+）取代到 NaGd 端元的整个组成范围，表明整个范围内都是均匀的。三价离子仅以一种配位环境掺入钨青铜结构，其表现出很强的配体-金属相互作用。对 NaGd（Eu）（MoO4）2 单晶的偏振依赖性测量确定了配位几何形状为 C2v 点对称。在钨青铜晶格中，Ca 位的 S4 对称可以通过第一配位球的微小运动转化为 C2v。
