Thermoelectric properties of Al82.6−xRe17.4Six (7⩽x⩽12) 1∕1-cubic approximants

Abstract

The thermoelectric power $S\left(T\right)$ and thermal conductivity $\kappa \left(T\right)$ were systematically studied for a series of ${\mathrm{Al}}_{82.6-x}{\mathrm{Re}}_{17.4}{\mathrm{Si}}_x$ $(7⩽x⩽12)$ $1∕1$-cubic approximants. We found that $S\left(T\right)$ of these approximants is characterized by large magnitude, sign reversal with varying composition, and nonlinear temperature dependence, all of which are also known as characteristics of the corresponding quasicrystals. The calculated $S\left(T\right)$ on the basis of the Boltzmann transport formula with accurately determined electronic structure showed extremely good agreement with the measured ones not only in their magnitude but also in the temperature and composition dependence. These results strongly indicate that these characteristic behaviors in $S\left(T\right)$ of the approximants and the corresponding quasicrystals are brought about by their characteristic electronic structure, i.e., the presence of a pseudogap across the Fermi level.