It is known that Yb-filled skutterudite with excellent thermoelectric performance is promising for a power generation device in the intermediate temperature region. Here we created a new approach to obtain nanostructured materials by adding Si to Co-overstoichiometric Yb-filled skutterudite through high-energy ball milling, which embedded bottom-up formed CoSi nanoparticles into grain-refining YbCoSb, synergistically resulting in the enhanced thermoelectric properties and room-temperature hardness. On one hand, the abundant grain boundaries and phase interfaces effectively blocked the propagation of medium-low frequency phonons, resulting in a lower lattice thermal conductivity. On the other hand, phase interfaces barrier nicely screened a portion of low-energy electrons, leading to an improved power factor. As a result, an enhanced peak value of ∼1.43 at 823 K and a promising average of ∼1.00 between 300 and 823 K were achieved in the YbCoSb/0.05CoSi sample. Meanwhile, such nanostructures also enhanced the hardness through the collective contributions of second phase and fine grain strengthening, which made skutterudite more competitive in practical application.
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Enhanced Thermoelectric Performance of Yb-Filled Skutterudite with Bottom-Up Formed CoSi Nanoparticles.
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National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin150001, China.
It is known that Yb-filled skutterudite with excellent thermoelectric performance is promising for a power generation device in the intermediate temperature region. Here we created a new approach to obtain nanostructured materials by adding Si to Co-overstoichiometric Yb-filled skutterudite through high-energy ball milling, which embedded bottom-up formed CoSi nanoparticles into grain-refining YbCoSb, synergistically resulting in the enhanced thermoelectric properties and room-temperature hardness. On one hand, the abundant grain boundaries and phase interfaces effectively blocked the propagation of medium-low frequency phonons, resulting in a lower lattice thermal conductivity.
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State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China.
Nanocomposites have become a widely popular way to assist in the enhancement of thermoelectric performance for filled skutterudites. Herein, we unveil the distinctive effect of Si doping on the classic YbCoSb. On the one hand, the reduced Yb filling fraction is accompanied by the in-situ precipitated CoSi nanoparticles, which not only enhances the power factor in the intermediate-low temperature range but also reduces electronic thermal conductivity for decreasing the carrier concentration.
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