High temperature electrical transport in Al-Pd-Mn quasicrystals

Abstract

We report measurements of the electrical conductivity /spl sigma/(T) and the Seebeck coefficient /spl alpha/(T) of a Czochralski-grown single phase quasicrystal of icosahedral Al/sub 70.8/Pd/sub 20.9/Mn/sub 8.3/ in the temperature range between 5 and 600 K. The electrical conductivity /spl sigma/(T) is only weakly temperature dependent. The values of the conductivity fall in the range between 630 and 740 (/spl Omega/ cm)/sup -1/. The Seebeck coefficient, /spl alpha/(T), increases monotonically with increasing temperature, reaches a maximum of 110 /spl mu/V/K at around 500 K after which the thermopower begins to decrease with increasing temperature. The power factor, /spl alpha//sup 2//spl sigma/T, is obtained from the electrical conductivity and thermopower data and at T=600 K, the power factor of icosahedral Al/sub 70.8/Pd/sub 20.9/Mn/sub 8.3/ reaches 0.5 W/m-K. This indicates that quasiperiodically structured alloys may be promising materials for thermoelectric applications at temperatures above room temperature.