Influence of hole-and phonon-nanoparticle scattering on the transport coefficients in BixSb1-xTe3 bulk nanostructures

Abstract

Investigations of nanostructured materials have already lead to an increase of the thermoelectric figure of merit. Probably a high figure of merit can be reached in bulk nanostructures fabricated by melt spinning with subsequent hot pressing. In the present work possible ranges of the transport coefficient modification due to the scattering of holes and phonons by nanoinclusions in such p-BixSb1-xTe3 bulk nanostructures are theoretically estimated. The dependence of the power factor on parameters of potential barriers or wells and on the carrier density was analyzed. The estimations showed that the reduction in lattice thermal conductivity (about 10%) for nanoinclusions of (Bi, Sb)2Te3 solid solution with different composition is much greater than the change in the power factor. Therefore corresponding increase of the thermoelectric figure of merit for this case is determined by phonon scattering. The influence of the nonlinearity of the phonon spectrum on the thermal conductivity change was analyzed, e.g. it was shown that in the case of sine-shaped instead of linear phonon spectrum the estimations gave two times higher thermal conductivity reduction.