scholarly journals On Landauer versus Boltzmann and full band versus effective mass evaluation of thermoelectric transport coefficients

2010 ◽  
Vol 107 (2) ◽  
pp. 023707 ◽  
Author(s):  
Changwook Jeong ◽  
Raseong Kim ◽  
Mathieu Luisier ◽  
Supriyo Datta ◽  
Mark Lundstrom
Keyword(s):  
Effective Mass ◽  
Transport Coefficients ◽  
Thermoelectric Transport ◽  
Full Band

Anisotropy Effects on the Thermoelectric Electronic Transport Coefficients

2015 ◽  
Vol 2 (1-2) ◽  
Author(s):  
Nicholas A. Mecholsky ◽  
Bothina Hamad ◽  
Lorenzo Resca ◽  
Ian L. Pegg ◽  
Marco Fornari
Keyword(s):  
Power Generation ◽  
Band Structure ◽  
Effective Mass ◽  
Critical Points ◽  
Electronic Transport ◽  
Transport Coefficients ◽  
Relative Orientation ◽  
Band Structures ◽  
Full Band

AbstractEngineering thermoelectric (TE) materials for applications in power generation and cooling requires an understanding of how anisotropy influences the TE properties. In this paper we use an angular-dependent, multivalley formalism to model the band structure and to explore the effect of anisotropy on the Seebeck and conductivity tensors. Specifically we explore the effect of degeneracy and relative orientation of the effective mass ellipsoids near critical points on the shape of these tensors. Examples of these types of anisotropic effects are explored within the above formalism and with the full band structures of two materials: half-Heusler ZrNiSn and (Sr,Ba)Nb

Composite Thermoelectrics - Exact Results and Calculational Methods

1991 ◽  
Vol 234 ◽  
Author(s):  
David J. Bergman ◽  
Ohad Levy
Keyword(s):  
Quality Factor ◽  
Computer Simulations ◽  
Lower Bounds ◽  
Theoretical Study ◽  
Transport Coefficients ◽  
Upper Bounds ◽  
Upper And Lower Bounds ◽  
Exact Results ◽  
Thermoelectric Transport

ABSTRACTA theoretical study of composite thermoelectric media has resulted in the development of a number of simple approximations, as well as some exact results. The latter include exact upper and lower bounds on the bulk effective thermoelectric transport coefficients of the composite and upper bounds on the bulk effective thermoelectric quality factor Ze. In particular, as a result of some exact theorems and computer simulations we conclude that Ze can never be greater than the largest value of Z in the different components that make up the composite.

scholarly journals Thermoelectric properties of the (an-)isotropic QGP in magnetic fields

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
He-Xia Zhang ◽  
Jin-Wen Kang ◽  
Ben-Wei Zhang
Keyword(s):  
Magnetic Field ◽  
Seebeck Coefficient ◽  
Strong Magnetic Field ◽  
Landau Level ◽  
Electric Fields ◽  
Chemical Potential ◽  
Thermal Structure ◽  
Transport Coefficients ◽  
Transverse Motion ◽  
Thermoelectric Transport

AbstractThe Seebeck effect and the Nernst effect, which reflect the appearance of electric fields along x-axis and along y-axis ($$E_{x}$$ E x and $$E_{y}$$ E y ), respectively, induced by the thermal gradient along x-axis, are studied in the QGP at an external magnetic field along z-axis. We calculate the associated Seebeck coefficient ($$S_{xx}$$ S xx ) and Nernst signal (N) using the relativistic Boltzmann equation under the relaxation time approximation. In an isotropic QGP, the influences of magnetic field (B) and quark chemical potential ($$\mu _{q}$$ μ q ) on these thermoelectric transport coefficients are investigated. In the presence (absence) of weak magnetic field, we find $$S_{xx}$$ S xx for a fixed $$\mu _{q}$$ μ q is negative (positive) in sign, indicating that the dominant carriers for converting heat gradient to electric field are negatively (positively) charged quarks. The absolute value of $$S_{xx}$$ S xx decreases with increasing temperature. Unlike $$S_{xx}$$ S xx , the sign of N is independent of charge carrier type, and its thermal behavior displays a peak structure. In the presence of strong magnetic field, due to the Landau quantization of transverse motion of (anti-)quarks perpendicular to magnetic field, only the longitudinal Seebeck coefficient ($$S_{zz}$$ S zz ) exists. Our results show that the value of $$S_{zz}$$ S zz at a fixed $$\mu _{q}$$ μ q in the lowest Landau level (LLL) approximation always remains positive. Within the effect of high Landau levels, $$S_{zz}$$ S zz exhibits a thermal structure similar to that in the LLL approximation. As the Landau level increases further, $$S_{zz}$$ S zz decreases and even its sign changes from positive to negative. The computations of these thermoelectric transport coefficients are also extended to a medium with momentum-anisotropy induced by initial spatial expansion as well as strong magnetic field.

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