Enhancement of thermoelectric power factor in composite thermoelectrics

Abstract

The analytical properties of macroscopic transport coefficients of two-component composites are first used to discuss the thermoelectric power factor of such a composite. It is found that the macroscopic power factor can sometimes be greater than the power factors of both of the pure components, with the greatest enhancement always achieved in a parallel slabs microstructure with definite volume fractions for the two components. Some interesting examples of actual mixtures are then considered, where the components are a “high quality thermoelectric” and a “benign metal,” leading to the conclusion that considerable enhancement of the power factor is often possible, with but a modest reduction in the thermoelectric figure of merit, compared to those of the high quality thermoelectric component. Two possibilities for fabricating real composites with such improved thermoelectric properties emerge from this study: a parallel slabs microstructure of benign metal and high quality thermoelectric, and a sintered collection of benign metal grains, each of them coated by a thin shell of high quality thermoelectric.

Nanostructure and thermoelectric properties of ReSi 2±x thin films

“…This agrees sufficiently with calculations using a model by Bergman [9], which shows a maximum of the power factor S 2 σ (σ = electrical conductivity) at 33% ReSi 1.75 in ReSi 2.22 matrix.…”

Enhanced thermoelectric performance of a new half-Heusler derivative Zr9Ni7Sn8 bulk nanocomposite: enhanced electrical conductivity and low thermal conductivity

“…40,41 This study demonstrates that the s and k of a composite can not be improved for high ZT, in comparison with that of either the best or worst thermoelectric parameter of the separate components of the composite, if the contribution from the phase interface/boundary is of little worth. 40,41 The thermoelectric properties calculated by them for the binary composite indicated that the ZT of the composite could never exceed the highest ZT of each separate component phase, although enhancement in the power factor could be achieved. The proof-of-principle of the EMA theory was demonstrated experimentally by Heremans et al 42 ,46-49 as the matrix phase deliver simultaneous improvement in the power factor and reduction in k leading to an increased ZT.…”

Eutectic Microstructure and Thermoelectric Properties of Mg2Sn

“…However, as shown theoretically by Bergman and Fel 14 and experimentally by Heremans and Jaworski, 15 it may be possible to enhance the power factor if the components are a ''high-quality thermoelectric'' and a ''benign metal.'' This paper is an extension of our earlier work [16][17][18] to systematically investigate the crystal growth, microstructure, composition and doping, and thermoelectric properties of the Mg 2 X compounds.…”