TY - JOUR
T1 - A comparative study of thermoelectric Cu2TrTi3S8 (Tr = Co and Sc) thiospinels
T2 - Enhanced Seebeck coefficient via electronic structure modification
AU - Hashikuni, Katsuaki
AU - Suekuni, Koichiro
AU - Usui, Hidetomo
AU - Chetty, Raju
AU - Ohta, Michihiro
AU - Takabatake, Toshiro
AU - Ohtaki, Michitaka
N1 - Funding Information:
We thank Y. Shibata for the EPMA performed at the Natural Science Center for Basic Research and Development, Hiroshima University. The authors would like to thank Enago ( www.enago.jp ) for the English language review. This work was financially supported by JSPS KAKENHI (Grant-in-Aid for JSPS Fellows) JP19J12916 (K. H.), JSPS KAKENHI Grant Nos. JP17H04951 and JP20H02440 (K. S.), grant from the International Joint Research Program for Innovative Energy Technology funded by METI , and grant from JST CREST Grant Nos. JPMJCR16Q6 and JPMJCR20Q4 .
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/8/5
Y1 - 2021/8/5
N2 - 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)S6 octahedra. 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 for Tr = Sc and Tr = Co, the Seebeck coefficient was remarkably enhanced for Tr = Co as compared to that for Tr = 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 at y = 1–1.5) was achieved for the Co-substituted samples at 673 K.
AB - 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)S6 octahedra. 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 for Tr = Sc and Tr = Co, the Seebeck coefficient was remarkably enhanced for Tr = Co as compared to that for Tr = 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 at y = 1–1.5) was achieved for the Co-substituted samples at 673 K.
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U2 - 10.1016/j.jallcom.2021.159548
DO - 10.1016/j.jallcom.2021.159548
M3 - Article
AN - SCOPUS:85102879698
SN - 0925-8388
VL - 871
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 159548
ER -