A Chemical Understanding of the Band Convergence in Thermoelectric CoSb3 Skutterudites: Influence of Electron Population, Local Thermal Expansion, and Bonding Interactions

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• 作者：Riley Hanus ; Xingyu Guo ; Yinglu Tang ; Guodong Li ; G. Jeffrey Snyder ; Wolfgang G. Zeier
• 刊名：Chemistry of Materials
• 出版年：2017
• 出版时间：February 14, 2017
• 年：2017
• 卷：29
• 期：3
• 页码：1156-1164
• 全文大小：550K
• ISSN：1520-5002

文摘

N-Type skutterudites, such as Yb_xCo₄Sb₁₂, have recently been shown to exhibit high valley degeneracy with possible band convergence, explaining the excellent thermoelectric efficiency of these materials. Using a combined theoretical and experimental approach involving temperature-dependent synchrotron diffraction, molecular orbital diagrams, and computational studies, the chemical nature of critical features in the band structure is highlighted. We identify how n-type doping on the filler site induces structural changes that are observed in both the diffraction data and computational results. Additionally, we show how chemical n-type doping slightly alters the electronic band structure, moving the high-valley degeneracy secondary conduction band closer to the primary conduction band and thus inducing band convergence.