Department of Applied Chemistry, Faculty of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
Inorg Chem. 2011 May 2;50(9):3901-6. doi: 10.1021/ic102077k. Epub 2011 Mar 29.
We prepared a new binary lanthanum germanide, LaGe(3), under high-pressure and high-temperature conditions (3-12 GPa, 500-1200 °C). It crystallizes in the BaPb(3) structure (the space group R ̅3m) with lattice constants of a = 6.376(1) Å, c = 22.272(3) Å, and V = 784.1(2) Å(3). We refined the structure using Rietveld analysis from X-ray powder data. The structure is composed of two types of close-packed atom layers. In one layer, every La atom is surrounded solely by Ge atoms with the same distance of 3.188 Å. The other layer contains Ge(3) regular, triangular cluster units with a Ge-Ge distance of 2.634 Å. The electron localization function and crystal orbital Hamilton population calculations suggest that the triangular cluster is composed of three Ge-Ge covalent bonds and that each Ge atom has a lone pair. The temperature dependence of the magnetic susceptibility and electrical conductivity measurements revealed that LaGe(3) is metallic and shows superconductivity at 7.4 K. This critical temperature is highest for the La-Ge system.
我们在高温高压条件下（3-12 GPa，500-1200 °C）制备了一种新的二元镧锗化物 LaGe(3)。它结晶于 BaPb(3)结构（空间群 R ̅3m），晶格常数为 a = 6.376(1) Å, c = 22.272(3) Å, 和 V = 784.1(2) Å(3)。我们使用 X 射线粉末数据的 Rietveld 分析对结构进行了精修。该结构由两种类型的密堆积原子层组成。在一层中，每个 La 原子仅被距离为 3.188 Å 的 Ge 原子包围。另一层包含具有 2.634 Å Ge-Ge 距离的 Ge(3)规则三角形簇单元。电子局域函数和晶体轨道哈密顿人口计算表明，三角形簇由三个 Ge-Ge 共价键组成，每个 Ge 原子都有一个孤对电子。磁 Susceptibility 和电导率测量的温度依赖性表明，LaGe(3)是金属的，并在 7.4 K 时表现出超导性。这个临界温度是 La-Ge 体系中最高的。
