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A2: Medium temperature materials
The synthesis of incongruent melt Higher Manganese Silicides compounds requires unpractically high cooling rate to avoid the decomposition of the liquid phase into MnSi and Si, which degrade their thermoelectric performance [1, 2]. On the other hand, the alternative preparation method via solid state reaction encounters the slow diffusion rate of Si due to its stable structure.
In this work, a simple and effective process is used to synthesize Higher Manganese Silicides, involving ball milling under soft conditions to obtain the homogeneous mixtures of constituent elements, and subsequent spark plasma sintering for a direct solid state reaction. We demonstrate that the wet milling process in hexane results in finer particles, which improves the reaction rate. The materials obtained by wet milling and spark plasma sintering contain pure phases of Higher Manganese Silicides with better thermoelectric performance than the ones obtained through dry milling. The experimental process and thermoelectric properties of the obtained compounds will be discussed in details. With further optimization, our method is very promising for industrial production to produce Higher Manganes Silicides for thermoelectric applications.
- I. Kawasumi et al., J. Mater. Sci. 16, 355 (1981)
- W. Luo et al., J. Electron. Mater. 40, 1233 (2011)