Low thermal conductivity of Al-based icosahedral quasicrystals and approximants

We investigated, in this study, the thermal conductivity of the icosahedral quasicrystals and their corresponding approximants, both of which are regarded as candidates for the new thermoelectric materials because of their possession of a small thermal conductivity less than a few W / m K and a large thermoelectric power up to ~ plusmn100 muV / K . As a consequence of the present experiments, we found that the quasicrystals possess a smaller lattice thermal conductivity than that of the corresponding approximants of the similar local atomic arrangements and other crystalline compounds obtained at a similar composition. By analyzing the thermal conductivity in terms of lattice constants, we realized that the extremely small thermal conductivity of the icosahedral quasicrystals is most likely brought about by the infinitely large lattice constant ( a = infin ) rather than by the specific local atomic arrangements nor the quasiperiodic ordering. We also found that the averaged atomic weight and the local atomic arrangements significantly affect the thermal conductivity of the quasicrystals as those in the crystalline materials.