New Insights into the Role of Dislocation Engineering in N-type Filled Skutterudite CoSb3
Dislocation engineering has recently recognized as an effective approach to develop high-performance thermoelectric materials. However, to date, the nature of dislocation engineering for performance enhancement has remained elusive in bulk materials, because the introduction of dislocations is normally accompanied by the change of material’s composition that leads to more variables in comparing and analyzing transport properties. Here, taking the Yb filled Skutterudite CoSb3 as a typical example, we first clearly unveil the critical role of dislocation arrays, introduced by a liquid-phase compaction process, on electron and phonon transport behavior. Due to the fact that the dislocation width is comparable with the electron mean free path, dislocation arrays effectively screen the low-energy carriers and induce the carrier filtering effect, which leads to the remarkable enhancement of both Seebeck coefficient and power factor. More importantly, beyond the classical theory that the reduction of thermal conductivity is merely caused by the targeted phonon scattering via dislocations, we first discover that dislocation arrays result in the lattice softening and strengthening bond anharmonicity simultaneously, both of which significantly impede the normal heat conduction process. Benefited from dislocation engineering coupled with tuning Yb filling fraction, we demonstrate that a record-high thermoelectric figure of merit ZT of 1.54 at 873 K among the n-type single-filled Skutterudite CoSb3. Our work not only highlights the promising prospect of Yb filled Skutterudite CoSb3 for energy harvesting but also first clearly unveils the critical role of dislocation engineering for ZT enhancement.