2, University of Chinese Academy of Sciences, Shanghai, , China
Higher Manganese Silicide materials have the advantage of environmental-friendly, low-cost, and stable. Cobalt has one more valence electron than manganese, thus the carrier concentration can be decreased when manganese is replaced by cobalt. In addition, the lattice distortion can also be induced. Thus, the lattice thermal conductivity could be reduced too. We adopted arc melting, high temperature annealing and SPS sintering techniques to get the MnSi1.72 and the Co-doped samples (1%-4% substitution proportion). After measuring the properties, we found that the substituted Co obviously decreases the electric conductivity and lattice thermal conductivity while the Seebeck decreases slightly, leading to a zT of 0.44 when the Co amount is 4%. When the Co amount is over 4%, CoSi2 impurity phase is observed in the materials.