TY - JOUR
T1 - Effect of Sn oxides on the thermal conductivity of polycrystalline SnSe
AU - Isotta, Eleonora
AU - Toriyama, Michael Y.
AU - Adekoya, Adetoye H.
AU - Shupp, Rolland
AU - Snyder, G. Jeffrey
AU - Zevalkink, Alexandra
N1 - Funding Information:
The authors would like to acknowledge helpful discussions with Prof. Donald Morelli, Prof. Jason Nicholas, and Genzhi Hu of Michigan State University. We would further like to acknowledge the help of Prof. Carl Boehlert, Tanzilur Raman, and Dr. Per Askeland of Michigan State University for sample polishing and SEM imaging, as well as Prof. Paolo Scardi of University of Trento for the Rietveld analysis. This research was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under award number DE-SC0019252. M.Y.T. is funded by the United States Department of Energy through the Computational Science Graduate Fellowship (DOE CSGF) under grant number DE-SC0020347. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology.
Funding Information:
The authors would like to acknowledge helpful discussions with Prof. Donald Morelli, Prof. Jason Nicholas, and Genzhi Hu of Michigan State University. We would further like to acknowledge the help of Prof. Carl Boehlert, Tanzilur Raman, and Dr. Per Askeland of Michigan State University for sample polishing and SEM imaging, as well as Prof. Paolo Scardi of University of Trento for the Rietveld analysis. This research was supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under award number DE-SC0019252 . M.Y.T. is funded by the United States Department of Energy through the Computational Science Graduate Fellowship (DOE CSGF) under grant number DE-SC0020347 . This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology.
Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/2
Y1 - 2023/2
N2 - SnSe is a promising thermoelectric material, with intrinsically low lattice thermal conductivity, κL. Surprisingly, in several reports, polycrystalline samples are found to have a higher thermal conductivity than single crystals. This disparity has been attributed to trace amounts of thermally conductive Sn oxides at the grain boundaries of polycrystalline samples. The same culprit was recently proposed to explain the reduction of κL in purified, oxide-free, SnSe polycrystals. Here, we test this hypothesis by: (i) tuning the type of oxide in SnSe by exploiting thermodynamic stability regions, since Sn-rich or Sn-poor compositions favour the formation of SnO or SnO2, respectively; and (ii) varying the quantity of SnO2 by intentionally oxidizing SnSe powder before consolidation, to obtain samples with quantifiable amounts - up to 15% - of SnO2. We find that the κL of SnSe is impervious to changes in the type or the amount of Sn oxide present in the samples. Our results show that a simple “rule of mixtures” cannot be used to estimate the effect of grain boundary oxides on the thermal conductivity of SnSe. These results call for an improved understanding of the intriguing thermal transport mechanisms in SnSe and numerous other systems where a two-phase transport is presumed.
AB - SnSe is a promising thermoelectric material, with intrinsically low lattice thermal conductivity, κL. Surprisingly, in several reports, polycrystalline samples are found to have a higher thermal conductivity than single crystals. This disparity has been attributed to trace amounts of thermally conductive Sn oxides at the grain boundaries of polycrystalline samples. The same culprit was recently proposed to explain the reduction of κL in purified, oxide-free, SnSe polycrystals. Here, we test this hypothesis by: (i) tuning the type of oxide in SnSe by exploiting thermodynamic stability regions, since Sn-rich or Sn-poor compositions favour the formation of SnO or SnO2, respectively; and (ii) varying the quantity of SnO2 by intentionally oxidizing SnSe powder before consolidation, to obtain samples with quantifiable amounts - up to 15% - of SnO2. We find that the κL of SnSe is impervious to changes in the type or the amount of Sn oxide present in the samples. Our results show that a simple “rule of mixtures” cannot be used to estimate the effect of grain boundary oxides on the thermal conductivity of SnSe. These results call for an improved understanding of the intriguing thermal transport mechanisms in SnSe and numerous other systems where a two-phase transport is presumed.
KW - SnO
KW - SnSe
KW - Ternary phase diagram
KW - Thermal conductivity
KW - Thermoelectricity
KW - Tin oxide
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U2 - 10.1016/j.mtphys.2023.100967
DO - 10.1016/j.mtphys.2023.100967
M3 - Article
AN - SCOPUS:85146055509
SN - 2542-5293
VL - 31
JO - Materials Today Physics
JF - Materials Today Physics
M1 - 100967
ER -