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Issue 14, 2018
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Enhancement of thermoelectric performance via weak disordering of topological crystalline insulators and band convergence by Se alloying in Pb0.5Sn0.5Te1 − xSex

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Abstract

Topological crystal insulators (TCIs) that have an even number of topologically protected Dirac bands driven by crystalline mirror symmetry have attracted much attention in condensed matter physics. Here, we demonstrate that a weak disordering in the topological crystalline state can enhance thermoelectric performance significantly due to highly dispersive band dispersion and high band degeneracy which guarantee high electrical mobility and a high Seebeck coefficient, respectively. When we perturb a crystalline mirror symmetry by Se-doping in TCI Pb0.5Sn0.5Te1 − xSex, the topological state becomes weak so that it eventually evolves the normal state. We experimentally prove the topological phase transition concerning Se concentration by X-ray Absorption Spectroscopy (XAS) and extended X-ray absorption Fine Structure (EXAFS) analysis. Small crystalline perturbation by Se doping (x = 0.05) significantly enhances thermoelectric performance due to the simultaneous enhancement of electrical conductivity and the Seebeck coefficient. Therefore, we report an exceptionally high ZT value of 1.9 at 800 K for the x = 0.05 compound which is a 313% enhancement of ZT compared with the pristine compound. This research proposes a new strategy for exploring high-performance thermoelectric materials by weak disordering of topological crystalline Dirac semimetals.

Graphical abstract: Enhancement of thermoelectric performance via weak disordering of topological crystalline insulators and band convergence by Se alloying in Pb0.5Sn0.5Te1 − xSex

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Publication details

The article was received on 12 Jan 2018, accepted on 26 Feb 2018 and first published on 26 Feb 2018


Article type: Paper
DOI: 10.1039/C8TA00381E
Citation: J. Mater. Chem. A, 2018,6, 5870-5879
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    Enhancement of thermoelectric performance via weak disordering of topological crystalline insulators and band convergence by Se alloying in Pb0.5Sn0.5Te1 − xSex

    D. Ginting, C. Lin, G. Kim, J. H. Yun, B. Yu, S. Kim, K. Ahn and J. Rhyee, J. Mater. Chem. A, 2018, 6, 5870
    DOI: 10.1039/C8TA00381E

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