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Chemical Modification and Energetically Favorable Atomic Disorder of a Layered Thermoelectric Material TmCuTe 2 Leading to High Performance
Author(s) -
Lin Hua,
Chen Hong,
Shen JinNi,
Chen Ling,
Wu LiMing
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201404453
Subject(s) - substructure , thermoelectric effect , materials science , thermoelectric materials , seebeck coefficient , stacking , vacancy defect , thermal conductivity , electrical resistivity and conductivity , semiconductor , crystal structure , atom (system on chip) , band gap , condensed matter physics , crystallography , thermodynamics , optoelectronics , chemistry , composite material , physics , electrical engineering , structural engineering , organic chemistry , computer science , embedded system , engineering
Thermoelectric (TE) materials have continuously attracted interest worldwide owing to their capability of converting heat into electricity. However, discovery and design of new TE material system remains one of the greatest difficulties. A TE material, TmCuTe 2 , has been designed by a substructure approach and successfully synthesized. The structure mainly features CuTe 4 ‐based layers stacking along the c axis that are separated by Tm 3+ cations. Such an intrinsic Cu site vacancy structure undergoes a first‐order phase transition at around 606 K driven by the energetically favorable uniform Cu atom re‐distribution on the covalent CuTe 4 ‐based layer substructure, as shown by crystal structure simulations and variable‐temperature XRD data. Featured with very low thermal conductivity (ca. 0.6 W m −1 K −1 ), large Seebeck coefficient (+185 μV K −1 ), and moderate electrical conductivity (220 S cm −1 ), TmCuTe 2 has a maximum ZT of 0.81 at 745 K, which is nine times higher than the value of 0.09 for binary Cu 2 Te, thus making it a promising candidate for mid‐temperature TE applications. Theoretical studies uncover the electronic structure modifications from the metallic Cu 2 Te to the narrow gap semiconductor TmCuTe 2 that lead to such a remarkable performance enhancement.