Thermal conductivity of the Al_82.6−xMn_17.4Si_x and Al_82.6−xRe_17.4Si_x 1/1-cubic approximants

Abstract

Thermal conductivity (κ) of the Al_{82.6− x} Mn_17.4Si _x and Al_{82.6− x} Re_17.4Si _x 1/1-cubic approximants was investigated with varying Si concentration x over a wide temperature range from 2 K to 300 K. Behaviors in κ observed for these 1/1-cubic approximants were essentially the same with those reported for the corresponding icosahedral quasicrystals; very small magnitude lower than 4.5 W/m K, small contribution of electrons, and possession of a local maximum and a local minimum around 30 ∼ 50 K and 100 ∼ 200 K, respectively. By analyzing measured κ in terms of local atomic structure, we revealed that the lattice thermal conductivity is greatly reduced by combination of small group velocity of phonons and enhanced umklapp process of phonon-scattering. Those characteristics were caused by large lattice constant and vacancies in the structure.