Enhanced Thermoelectric Performance of Yb-Filled Skutterudite with Bottom-Up Formed CoSi2 Nanoparticles

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 CoSi2 nanoparticles into grain-refining Yb0.25Co4Sb12, 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 ZT value of similar to 1.43 at 823 K and a promising average ZT of similar to 1.00 between 300 and 823 K were achieved in the Yb0.25Co4Sb12/ 0.05CoSi(2) 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.

Automated summary

Adding Si to Yb-filled skutterudite through high-energy ball milling creates nanostructured materials with embedded CoSi2 nanoparticles, resulting in enhanced thermoelectric performance and hardness.