Effect of Small Amounts of Ni and Co Doping on p-type Al-doped Iron Disilicide

Kurzfassung

Alloys of p-type iron disilicide FeAl0.04Si2.00 added with small amounts of n-type dopants Ni and Co Fe1-xMxAl0.04Si2 (M = Ni or Co) were prepared and characterized. Hall measurements in the temperature range of 25 – 300 K shows that the Hall concentration is between 5.9 ×1018 cm-3 and 1.5 ×1019 cm-3, and Hall mobility is within 5.4 – 18 cm2/Vs. The carrier concentration of FeAl0.04Si2.00 is reduced by partial compensation of Ni or Co. The mobility is slightly enhanced above 250 K by compensating doping of Ni or Al with Co. Thermoelectric properties were measured from room temperature up to 1000K. The electrical conductivity is decreased by the compensation doping, while Seebeck coefficient and thermal conductivity are increased. A reduction of the thermal conductivity as could be expected from alloying with an additional element is not observed. The maximum of the figure of merit (ZT = 0.11) is obtained at 830 K for uncompensated FeAl0.04Si2.00.