Rapid fabrication of pure p-type filled skutterudites with enhanced thermoelectric properties via a reactive liquid-phase sintering

Filled skutterudites have great potential for power generation. However, the conventional melting–quenching–annealing–sintering process requires a time-consuming annealing process to accomplish the phase transformation. A new strategy to realize the complete phase transformation in a short time is an urgent need for filled skutterudite. In this study, a modifying reactive liquid-phase sintering enabled by introducing the extra BaSb₃ in the spark plasma sintering process was successfully applied to fabricate pure BaFe₄Sb₁₂ skutterudites in less than 30 h. It is found that increasing BaSb₃ liquid content can effectively promote the phase transformation to BaFe₄Sb₁₂ skutterudite through accelerating the chemical reaction between the quenched mixtures during the sintering process. However, an abnormal grain growth would take place with further increasing the liquid content. An optimal ZT value of 0.62 at 800 K was achieved for the BaFe₄Sb₁₂ skutterudite due to the enhanced Seebeck coefficient and the increased electrical conductivity as well as the decreased lattice thermal conductivity induced by the single-phase composition. This work demonstrates that pure filled skutterudite with enhanced TE performance can be fabricated by the simple and efficient reactive liquid-phase sintering without longtime annealing process.