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Understanding of the Extremely Low Thermal Conductivity in High‐Performance Polycrystalline SnSe through Potassium Doping
Author(s) -
Chen YueXing,
Ge ZhenHua,
Yin Meijie,
Feng Dan,
Huang XueQin,
Zhao Wenyu,
He Jiaqing
Publication year - 2016
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201602652
Subject(s) - materials science , spark plasma sintering , crystallite , thermal conductivity , doping , grain boundary , dopant , analytical chemistry (journal) , electrical resistivity and conductivity , condensed matter physics , sintering , composite material , metallurgy , microstructure , optoelectronics , chemistry , physics , chromatography , electrical engineering , engineering
P‐type polycrystalline SnSe and K 0.01 Sn 0.99 Se are prepared by combining mechanical alloying (MA) and spark plasma sintering (SPS). The highest ZT of ≈0.65 is obtained at 773 K for undoped SnSe by optimizing the MA time. To enhance the electrical transport properties of SnSe, K is selected as an effective dopant. It is found that the maximal power factor can be enhanced significantly from ≈280 μW m −1 K −2 for undoped SnSe to ≈350 μW m −1 K −2 for K‐doped SnSe. It is also observed that the thermal conductivity of polycrystalline SnSe can be enhanced if the SnSe powders are slightly oxidized. Surprisingly, after K doping, the absence of Sn oxides at grain boundaries and the presence of coherent nanoprecipitates in the SnSe matrix contribute to an impressively low lattice thermal conductivity of ≈0.20 W m −1 K −1 at 773 K along the sample section perpendicular to pressing direction of SPS. This extremely low lattice thermal conductivity coupled with the enhanced power factor results in a record high ZT of ≈1.1 at 773 K along this direction in polycrystalline SnSe.