Structural Evolution of the Binary System Ba-Si under High-pressure and High-temperature Conditions
Structural Evolution of the Binary System Ba-Si under High-pressure and High-temperature Conditions
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DOI：
10.1515/znb-2006-1205
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发表时间：
2006-12
期刊：
影响因子：
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通讯作者：
S. Yamanaka;S. Maekawa
中科院分区：
文献类型：
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作者：
S. Yamanaka;S. Maekawa
在1000 °C、15 GPa的压力下处理Ba_8Si_46笼形化合物，或在类似的高压高温条件下处理BaSi_2和Si的化学计量混合物，制备了一种新的富硅二元化合物BaSi_6。Rietveld精修表明BaSi_6与EuGa_2Ge_4是类质同象的，晶体空间群为Cmcm，晶格参数a = 4.485（1），B = 10.375（2），c = 11.969（3）nm。每个Ba原子被18个Si原子包围在一个不规则形状的多面体@Si18中。多面体通过共享面连接以形成沿a轴沿着的含Ba隧道。迄今为止，二元系中Si/Ba原子比大于2的富硅化合物都是在高温高压条件下制备的。随着制备压力的增加，化合物的Si/Ba比有增加的趋势。
A new silicon-rich binary compound BaSi6 has been prepared by the treatment of the Ba8Si46 clathrate compound under a pressure of 15 GPa at 1000 °C, or from a stoichiometric mixture of BaSi2 and Si by treatment under similar high-pressure and high-temperature conditions. The Rietveld refinements revealed that BaSi6 is isomorphous with EuGa2Ge4, and crystallizes with space group Cmcm and the lattice parameters a = 4.485(1), b = 10.375(2), and c = 11.969(3) Å . Each Ba atom is surrounded by 18 Si atoms in an irregularly shaped polyhedron @Si18. The polyhedra are connected by sharing faces to form Ba containing tunnels along the a axis. All of the Si-rich compounds so far with atomic ratios Si/Ba > 2 in the binary system have been prepared only under high-pressure and high-temperature conditions. There is a general tendency that the Si/Ba ratio of the compounds increases with an increase of the pressure in the preparation.