Effective medium theory based modeling of the thermoelectric properties of composites: comparison between predictions and experiments in the glass-crystal composite system Si sub(10)As sub(15)Te sub( 75)-Bi sub(0.4)Sb sub(1.6) Te sub(3)

We report on the theoretical predictions of the effective medium theory (EMT) and its generalized version taking into account percolation theory (GEMT) on the thermoelectric properties of composites based on Landauer and Sonntag's equations. The results were tested experimentally on composites...

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Bibliographic Details
Published in:Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2015-10, Vol.3 (42), p.11090-11098
Main Authors: Vaney, J-B, Piarristeguy, A, Ohorodniichuck, V, Ferry, O, Pradel, A, Alleno, E, Monnier, J, Lopes, E B, Goncalves, AP, Delaizir, G, Candolfi, C, Dauscher, A, Lenoir, B
Format: Article
Language:English
Subjects:
Crystal structure
Effective medium theory
Electrical resistivity
Evolution
Mathematical analysis
Mathematical models
Thermal conductivity
Thermoelectricity
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Summary:We report on the theoretical predictions of the effective medium theory (EMT) and its generalized version taking into account percolation theory (GEMT) on the thermoelectric properties of composites based on Landauer and Sonntag's equations. The results were tested experimentally on composites composed of the glassy phase Si sub(10)As sub(15)Te sub( 75) and the crystalline phase Bi sub(0.4)Sb sub(1.7)Te sub(3). The evolution of the electrical resistivity and thermal conductivity with the fraction of crystalline phase matches very well the experimental data, although the GEMT model fails to predict the thermopower. A better agreement between theory and experiment could be obtained by combining the principles of the GEMT and the Webman-Jortner-Cohen models. Despite the fact that the GEMT model originally predicts the possibility to optimize the dimensionless figure of merit ZTof composites by adjusting the fraction and the values of the transport properties of each phase, the new model developed rules out any beneficial influence on the ZTvalues. These results confirm within a different framework the early conclusions of Bergman regarding the impossibility of improving the ZTvalues using multi-phased materials.
ISSN:2050-7526
2050-7534
DOI:10.1039/c5tc02087e