Synthesis and thermoelectric properties of silicon- and manganese-doped Ru1−xFexAl2

Polycrystalline Si- and Mn-doped Ru1−xFexAl2 (x = 0.0, 0.1, 0.15) were prepared by arc melting. Their thermoelectric and transport properties were measured from room temperature to around 1000 K. The thermal conductivity decreased with increasing Fe composition of Ru1−xFexAl2 (x = 0.0, 0.1, 0.15). As for their electrical properties, Mn-doped samples showed p-type conduction in the whole temperature range. Mn doping caused both the electrical resistivity and the positive Seebeck coefficient to decrease due to the increase of carrier concentration. Si-doped samples showed n-type conduction below 400 K, and the sign of the Seebeck coefficient changed to positive above 500 K because of the heavy hole excitation. The ZT value reached 0.17 for p-type Ru0.85Fe0.15Al2 and 0.05 for n-type Ru0.85Fe0.15Al1.95Si0.05.