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Relating phase transition heat capacity to thermal conductivity and effusivity in Cu 2 Se
Author(s) -
Brown David R.,
Heijl Richard,
Borup Kasper A.,
Iversen Bo B.,
Palmqvist Anders,
Snyder G. J.
Publication year - 2016
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201600160
Subject(s) - thermal effusivity , thermal diffusivity , thermal conductivity , heat capacity , differential scanning calorimetry , thermodynamics , seebeck coefficient , materials science , thermoelectric materials , thermal conductivity measurement , thermoelectric effect , phase transition , thermal , condensed matter physics , chemistry , analytical chemistry (journal) , thermal resistance , thermal contact conductance , composite material , physics , chromatography
Accurate measurement of thermal conductivity is essential to determine the thermoelectric figure‐of‐merit, zT . Near the phase transition of Cu 2 Se at 410 K, the transport properties change rapidly with temperature, and there is a concurrent peak in measured heat capacity from differential scanning calorimetry (DSC). Interpreting the origin as a broad increase in heat capacity or as a transient resulted in a three‐fold difference in the reported zT in two recent publications. To resolve this discrepancy, thermal effusivity was deduced from thermal conductivity and diffusivity measurements via the transient plane source (TPS) method and compared with that calculated from thermal diffusivity and the two interpretations of the DSC data for heat capacity. The comparison shows that the DSC measurement gave the heat capacity relevant for calculation of the thermal conductivity of Cu 2 Se. The thermal conductivity calculated this way follows the electronic contribution to thermal conductivity closely, and hence the main cause of the zT peak is concluded to be the enhanced Seebeck coefficient. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)