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Thermoelectric Properties and Chemical Potential Tuning by K- and Se-Coalloying in (Pb 0.5 Sn 0.5 ) 1−x K x Te 0.95 Se 0.05

Title
Thermoelectric Properties and Chemical Potential Tuning by K- and Se-Coalloying in (Pb 0.5 Sn 0.5 ) 1−x K x Te 0.95 Se 0.05
Authors
Ginting D.Lin C.-C.Kim G.Back S.Y.Won B.Cho H.Yun J.H.So H.S.Lee H.Yu B.-K.Kim S.-J.Rhyee J.-S.
Ewha Authors
김성진
SCOPUS Author ID
김성진scopus
Issue Date
2019
Journal Title
Electronic Materials Letters
ISSN
1738-8090JCR Link
Citation
Electronic Materials Letters vol. 15, no. 3, pp. 342 - 349
Keywords
Dirac semimetalNano precipitationThermoelectricTopological crystalline insulatorZT
Publisher
The Korean Institute of Metals and Materials
Indexed
SCIE; SCOPUS; KCI scopus
Document Type
Article
Abstract
Abstract: Topological crystal insulator (TCI) and topological Dirac semimetals have topologically nontrivial surface and bulk state, respectively. The parent compound of Pb 0.5 Sn 0.5 Te exhibiting TCI band inversion has particle-hole symmetry owing to the gapless Dirac band implying a strong electron–hole bipolar compensation in Seebeck coefficient. We recently reported that weak perturbation of TCI state can enhance thermoelectric performance significantly due to highly dispersive and degenerated energy bands. It is a great interest that the further increase of chemical potential has beneficiary to thermoelectric performance in the vicinity of topological phase transition. Here we investigate the thermoelectric properties of the co-doping effect by K and Se in (Pb 0.5 Sn 0.5 ) 1−x K x Te 0.95 Se 0.05 (x = 0.0, 0.005, 0.010, 0.015, 0.02) compounds. K-doping increases the band gap from 0.15 eV (Pb 0.5 Sn 0.5 Te) to 0.21 eV (x = 0.05) as well as increasing chemical potential resulting in the suppression of bipolar diffusion effect. In spite of the suppression of bipolar diffusion effect by K-doping, the power factor in K-doped compound is decreased significantly than the one of non-doped Pb 0.5 Sn 0.5 Te 0.95 Se 0.05 compound. It indicates that when we increase chemical potential further on the breaking of topological band inversion, the thermoelectric performance is deteriorated because the chemical potential resides far from the linear band dispersions which become conventional material. The ZT for the K-doped (Pb 0.5 Sn 0.5 ) 1−x K x Te 0.95 Se 0.05 is obtained as 0.91 at 750 K for x = 0.017 which is increased as much as 99% comparing to the pristine compound Pb 0.5 Sn 0.5 Te but it is reduced value (51.5%) comparing to those of Pb 0.5 Sn 0.5 Te 0.95 Se 0.05 compound. We believe that this research is valuable on the confirmation that the weak perturbation of topological state and appropriate chemical potential tuning are important criteria in high thermoelectric performance. Graphical Abstract: [Figure not available: see fulltext.]. © 2019, The Korean Institute of Metals and Materials.
DOI
10.1007/s13391-019-00130-1
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자연과학대학 > 화학·나노과학전공 > Journal papers
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