A comparative study of thermoelectric Cu2TrTi3S8 (Tr = Co and Sc) thiospinels: Enhanced Seebeck coefficient via electronic structure modification
A comparative study of thermoelectric Cu2TrTi3S8 (Tr = Co and Sc) thiospinels: Enhanced Seebeck coefficient via electronic structure modification
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DOI：
10.1016/j.jallcom.2021.159548
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发表时间：
2021-03
影响因子：
6.2
通讯作者：
Katsuaki Hashikuni;K. Suekuni;H. Usui;R. Chetty;M. Ohta;T. Takabatake;M. Ohtaki
中科院分区：
文献类型：
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作者：
Katsuaki Hashikuni;K. Suekuni;H. Usui;R. Chetty;M. Ohta;T. Takabatake;M. Ohtaki
采用热电测量和第一性原理计算相结合的方法研究了Cu_2TryTi_（4-y）S_8（Tr= Sc，Co）硫尖晶石的电子结构.硫尖晶石显示出n型和金属性质的导电网络组成的边缘共享的（Ti/Tr）S6八面体。Sc和Co取代Ti以类似的方式降低了电子载流子浓度，导致电阻率和塞贝克系数都增加。虽然Tr = Sc和Tr = Co的电阻率相当，但Tr = Co的Seebeck系数比Tr = Sc的显著提高。Co取代体系中的Seebeck系数的提高归因于Co-3d轨道部分取代Ti-3d轨道导致费米能级附近导带态密度的增加。由于电子结构的改变，在673 K时，Co取代样品的无量纲热电优值（ZT= 0.2 aty= 1-1.5）得到了提高。
We studied the electronic structures of Cu2TryTi4–yS8(Tr= Sc, Co) thiospinels by combining thermoelectric measurements and first-principles calculations. The thiospinels showed n-type and metallic properties governed by a conductive network composed of edge-shared (Ti/Tr)S6octahedra. The substitutions of Sc and Co for Ti decreased the electron carrier concentration in a similar manner, leading to increases in both the electrical resistivity and Seebeck coefficient. Although the electrical resistivity was equivalent forTr= Sc andTr= Co, the Seebeck coefficient was remarkably enhanced forTr= Co as compared to that forTr= Sc. The enhanced Seebeck coefficient in the Co-substituted system was ascribed to the increased density of states of conduction band near the Fermi level due to the partial replacement of Ti-3d orbitals by Co-3d orbitals. Owing to the electronic structure modification, a higher dimensionless thermoelectric figure of merit (ZT= 0.2 aty= 1–1.5) was achieved for the Co-substituted samples at 673 K.