Department of Physics, University of South Florida, Tampa, FL 33620, USA.
J Phys Condens Matter. 2010 Dec 8;22(48):485404. doi: 10.1088/0953-8984/22/48/485404. Epub 2010 Nov 17.
The low temperature thermal conductivity, resistivity, and Seebeck coefficient of single-crystal Na(8)Si(46) are investigated revealing the intrinsic low temperature transport properties of this material. Metallic conduction is observed, with a higher residual resistance ratio than any other known type I clathrate. Heat capacity together with thermal conductivity provide insight into the Na disorder inside the polyhedra formed by the Si framework. Single-crystal structural refinement and thermal property analyses reveal anisotropic disorder for Na inside the tetrakaidecahedra due to a reduction in the symmetry inside these polyhedra, unlike that for Na inside the dodecahedra.
研究了单晶 Na(8)Si(46) 的低温热导率、电阻率和塞贝克系数，揭示了这种材料的固有低温输运性质。观察到金属传导，其剩余电阻比任何其他已知的 I 型笼型化合物都高。热容与热导率一起提供了对 Si 框架形成的多面体内部 Na 无序的深入了解。单晶结构精修和热性能分析表明，由于这些多面体内部对称性的降低，四面体内部 Na 的各向异性无序与十二面体内部 Na 的无序不同。
