Enhanced thermoelectric performance through crystal field engineering in transition metal-doped GeTe
Enhanced thermoelectric performance through crystal field engineering in transition metal-doped GeTe
复制标题
通过过渡金属掺杂 GeTe 的晶体场工程增强热电性能
DOI：
10.1016/j.mtphys.2019.100094
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
T. Mori
中科院分区：
文献类型：
--
作者：
J. Shuai;X.J. Tan;Q. Guo;J.T. Xu;A. Gelle;R. Gautier;J.-F. Halet;F. Failamani;J. Jiang;T. Mori
GeTe中菱方相和立方相之间多价能带结构的变化为改变其热电性能提供了新的维度。在这里，我们报告的电子和热输运性能的协同优化菱面体GeTe掺杂过渡金属Ti。Ge_（1-x）Ti_xTe的Seebeck系数显著增加，相应的热导率降低。结构细化表明，Ti掺杂降低了晶格常数tc/aratio。密度泛函理论计算表明，受影响的晶体场，而不是Ti轨道是有助于价带收敛和塞贝克系数增强。进一步的优化结合了Bi替代的效果，以降低载流子浓度并引入更多的点缺陷。这项工作不仅证实了过渡金属元素作为GeTe基材料的有前途的掺杂剂，但也表明，操纵晶场效应的策略可以被利用作为一个直接的，但有效的路线，以提高热电性能。
The change of multivalence band structure configuration between rhombohedral and cubic phase in GeTe offers additional dimension to modify its thermoelectric properties. Here, we report the synergetic optimization of electronic and thermal transport properties in rhombohedral GeTe doped with transition metal Ti. The Seebeck coefficient of Ge1-xTixTe is significantly increased, and the corresponding thermal conductivity is decreased. The structure refinement shows that Ti doping could reduce the lattice constantc/aratio. Density functional theory calculations demonstrate that the affected crystal field rather than Ti orbitals is contributing to the valence band convergence and a Seebeck coefficient enhancement. Further optimization incorporates the effects of Bi substitution for reducing the carrier concentrations and introducing more point defects. This work not only confirms the transition metal elements as promising dopants for GeTe-based materials but also indicates that the strategy of manipulating the crystal field effect can be exploited as a direct but effective route for improving thermoelectric performance.