Zevalkink Alex, Swallow Jessica, Ohno Saneyuki, Aydemir Umut, Bux Sabah, Snyder G Jeffrey
Thermal Energy Conversion Technologies Group, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, USA.
Dalton Trans. 2014 Nov 14;43(42):15872-8. doi: 10.1039/c4dt02206h.
Zintl phases are attractive for thermoelectric applications due to their complex structures and bonding environments. The Zintl compounds Ca(5)Al(2)In(x)Sb(6)and Ca(5)Al(2)In(x)Sb(6) have both been shown to have promising thermoelectric properties, with zT values of 0.6 and 0.7, respectively, when doped to control the carrier concentration. Alloying can often be used to further improve thermoelectric materials in cases when the decrease in lattice thermal conductivity outweighs reductions to the electronic mobility. Here we present the high temperature thermoelectric properties of the Ca(5)Al(2-x)In(x)Sb(6)solid solution. Undoped and optimally Zn-doped samples were investigated. X-ray diffraction confirms that a full solid solution exists between the Al and In end-members. We find that the Al : In ratio does not greatly influence the carrier concentration or Seebeck effect. The primary effect of alloying is thus increased scattering of both charge carriers and phonons, leading to significantly reduced electronic mobility and lattice thermal conductivity at room temperature. Ultimately, the figure of merit is unaffected by alloying in this system, due to the competing effects of reduced mobility and lattice thermal conductivity.
由于其复杂的结构和键合环境，津特耳相在热电应用中具有吸引力。津特耳化合物Ca(5)Al(2)In(x)Sb(6)和Ca(5)Al(2)In(x)Sb(6)均已显示出具有良好的热电性能，在掺杂以控制载流子浓度时，其zT值分别为0.6和0.7。当晶格热导率的降低超过电子迁移率的降低时，合金化通常可用于进一步改善热电材料。在此，我们展示了Ca(5)Al(2 - x)In(x)Sb(6)固溶体的高温热电性能。研究了未掺杂和最佳锌掺杂的样品。X射线衍射证实，在Al和In端成员之间存在完全固溶体。我们发现，Al : In比例对载流子浓度或塞贝克效应影响不大。因此，合金化的主要作用是增加了电荷载流子和声子的散射，导致室温下电子迁移率和晶格热导率显著降低。最终，由于迁移率降低和晶格热导率的竞争效应，该系统中的品质因数不受合金化影响。
