Institute of Physical Chemistry, University of Vienna, Waehringerstrasse 42, A-1090 Wien, Austria.
Dalton Trans. 2012 Aug 7;41(29):8839-49. doi: 10.1039/c2dt30279a. Epub 2012 Jun 14.
The phase relations, crystal structure and thermoelectric properties of the type-I solid solution Ba(8)Ni(x)Si(46-x) were investigated. Based on X-ray diffraction, differential thermal analysis and electron probe microanalysis data, a partial phase diagram was constructed for the Si-rich part of ternary system Ba-Ni-Si at 800 °C. The solubility range of Ni in the clathrate-I phase at 800 °C was determined (2.9 ≤x≤ 3.8) and thermoelectric properties, namely electrical resistivity, Seebeck-coefficient and thermal conductivity, were measured in the temperature range from 300 to 850 K. A shift of the thermoelectric properties from a predominantly metallic to a more semiconducting behavior was observed for an increasing Ni-content. Density functional calculations revealed a significant decrease of the gap width in the density of states induced by the incorporation of Ni. Electrical resistivity and Seebeck coefficients for Ba(8)Ni(x)Si(46-x) with 3.3 ≤x≤ 3.8 have been modeled within the rigid band approximation.
研究了 I 型固溶体 Ba(8)Ni(x)Si(46-x)的相平衡、晶体结构和热电性能。基于 X 射线衍射、差热分析和电子探针微分析数据，在 800°C 下构建了三元体系 Ba-Ni-Si 的富硅部分的部分相图。确定了 I 型笼合物相中 Ni 的溶解度范围（2.9 ≤ x ≤ 3.8），并在 300 至 850 K 的温度范围内测量了其热电性能，即电阻率、塞贝克系数和热导率。随着 Ni 含量的增加，观察到热电性能从主要金属行为向更半导体行为的转变。密度泛函计算表明，由于 Ni 的掺入，导致了态密度中带隙宽度的显著减小。对于 3.3 ≤ x ≤ 3.8 的 Ba(8)Ni(x)Si(46-x)，电导率和塞贝克系数已在刚性带近似下进行了建模。
