Influence of in situ formed MoSi₂ inclusions on the thermoelectrical properties of an N-type silicon-germanium alloy

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• 作者：Katia Favier ; Guillaume Bernard-Granger ; Christelle Navone ; Mathieu Soulier ; Mathieu Boidot ; Jean Leforestier ; Julia Simon ; Jean-Claude Tedenac ; Didier Ravot
• 关键词：Thermoelectric materials ; Spark plasma sintering ; Transmission electron microscopy ; Silicon&ndash ; germanium alloys
• 刊名：Acta Materialia
• 出版年：February, 2014
• 年：2014
• 卷：64
• 期：Complete
• 页码：429-442
• 全文大小：5441 K

文摘

An N-type Si₉₂Ge₀₈ (7000 at. ppm P doping) powder (matrix) prepared by mechanical alloying was homogeneously mixed with 1.3 vol.% nanosized molybdenum. The 鈥渃omposite鈥?and matrix powders were sintered by spark plasma sintering, using optimized parameters. The as-sintered 鈥渃omposite鈥?material exhibits a dimensionless thermoelectrical figure of merit (ZT) of 鈭?.0 at 700 掳C. For the same temperature, the ZT value is only 0.7 for the as-sintered matrix alone. In the composite material, transmission electron microscopy observations enable the detection of nanosized (average diameter of 鈭?0 nm) MoSi₂ inclusions that formed in situ during sintering via the reaction between the native silicon-germanium matrix and the added molybdenum particles. The presence of such nanosized inclusions reduces significantly the lattice contribution to the thermal conductivity of the sintered 鈥渃omposite鈥?material, explaining the strong increase of the ZT parameter in comparison to the sintered matrix alone.