Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
Materials Science, California Institute of Technology, Pasadena, California 91125, USA.
Nat Mater. 2015 Dec;14(12):1223-8. doi: 10.1038/nmat4430. Epub 2015 Oct 5.
Filled skutterudites R(x)Co4Sb12 are excellent n-type thermoelectric materials owing to their high electronic mobility and high effective mass, combined with low thermal conductivity associated with the addition of filler atoms into the void site. The favourable electronic band structure in n-type CoSb3 is typically attributed to threefold degeneracy at the conduction band minimum accompanied by linear band behaviour at higher carrier concentrations, which is thought to be related to the increase in effective mass as the doping level increases. Using combined experimental and computational studies, we show instead that a secondary conduction band with 12 conducting carrier pockets (which converges with the primary band at high temperatures) is responsible for the extraordinary thermoelectric performance of n-type CoSb3 skutterudites. A theoretical explanation is also provided as to why the linear (or Kane-type) band feature is not beneficial for thermoelectrics.
填充型 skutterudites R(x)Co4Sb12 是出色的 n 型热电材料，因为它们具有高电子迁移率和高有效质量，同时由于填充原子进入空位而导致热导率降低。n 型 CoSb3 的有利电子能带结构通常归因于导带最小值处的三重简并，以及在更高载流子浓度下的线性能带行为，这被认为与掺杂水平增加时有效质量的增加有关。相反，通过结合实验和计算研究，我们表明，具有 12 个传导载流子口袋的二次传导带（在高温下与主带收敛）是 n 型 CoSb3 skutterudites 具有非凡热电性能的原因。还提供了一个理论解释，说明为什么线性（或 Kane 型）能带特征不利于热电。
