Traversing the Metal‐Insulator Transition in a Zintl Phase: Rational Enhancement of Thermoelectric Efficiency in Yb14Mn1−xAlxSb11
Traversing the Metal‐Insulator Transition in a Zintl Phase: Rational Enhancement of Thermoelectric Efficiency in Yb14Mn1−xAlxSb11
复制标题
DOI：
10.1002/adfm.200800298
复制
发表时间：
2008-09
影响因子：
19
通讯作者：
E. Toberer;Catherine A. Cox;S. Brown;T. Ikeda;A. May;S. Kauzlarich;G. J. Snyder
中科院分区：
文献类型：
--
作者：
E. Toberer;Catherine A. Cox;S. Brown;T. Ikeda;A. May;S. Kauzlarich;G. J. Snyder
对于高温热电应用，Yb14MnSb11在1273K时的最大热电优值(ZT)为∼1.0，尽管载流子浓度高于典型的热电材料，但仍有如此高的热电优值。在这里，我们通过发现金属Yb14MnSb11和半导体Yb14AlSb11之间的连续跃迁来降低载流子浓度。Yb14Mn1-xAlxSb11形成固溶体，其中自由载流子浓度根据Zintl价公式的预期逐渐变化。在整个跃迁过程中，电子性质服从带隙为0.5 eV、有效质量为3me的刚性带隙模型。随着载流子浓度的降低，观察到Seebeck系数的增加，但其代价是电阻率的增加。在最佳载流子浓度下，1223K时的最大ZT为1.3，是NASA最先进的Si0.8Ge0.2的两倍多。
For high temperature thermoelectric applications, Yb14MnSb11 has a maximum thermoelectric figure of merit (zT) of ∼1.0 at 1273 K. Such a high zT is found despite a carrier concentration that is higher than typical thermoelectric materials. Here, we reduce the carrier concentration with the discovery of a continuous transition between metallic Yb14MnSb11 and semiconducting Yb14AlSb11. Yb14Mn1‐xAlxSb11 forms a solid solution where the free carrier concentration gradually changes as expected from the Zintl valence formalism. Throughout this transition the electronic properties are found to obey a rigid band model with a band gap of 0.5 eV and an effective mass of 3 me. As the carrier concentration decreases, an increase in the Seebeck coefficient is observed at the expense of an increased electrical resistivity. At the optimum carrier concentration, a maximum zT of 1.3 at 1223 K is obtained, which is more than twice that of the state‐of‐the‐art Si0.8Ge0.2 flown by NASA.