Accelerated melting annealing synthesis of high-performance filled skutterudite through repeated quenching

The melt-annealing method is currently the main method for preparing the skutterudite materials and devices. However, its extensive utilization is impeded by a time-consuming annealing process. To address this issue, we have developed a melt-quenching-annealing-quenching procedure that significantly shortens the annealing time of Yb-filled CoSb3 skutterudite to only 1 day. Our findings confirm that quenching after annealing effectively promotes the formation of CoSb3 phase. Moreover, the reduced annealing time restricts grain growth. This outcome leads to a evident reduction in lattice thermal conductivity, taking into account the effect of the off-center Yb filler in voids distorting the crystal structure. Ultimately, a competitive zT of ∼1.25 is achieved at 823 K in Yb-filled CoSb3. This work provides a guidance for the rapid preparation of skutterudite by melt-annealing.