Nanostructuring and defect engineering are increasingly employed as processing strategies for thermoelectric performance enhancement, and special attention has been paid to nanostructured interfaces and dislocations that can effectively scatter low- and mid-frequency phonons. This work demonstrated that their combination was realized in Fe2O3-dispersed tetrahedrite (Cu12Sb4S13) nanocomposites, leading to significantly reduced thermal conductivities around 0.9 W m-1 K-1 at all temperatures and hence a high ZT value of ∼1.0, which increases by ∼33% compared with that of the matrix. The plausible enhancement mechanisms have been analyzed with an emphasis on the incorporation of magnetic γ-Fe2O3 nanoparticles (NPs) into Cu11.5Ni0.5Sb4S13, leading to various nanostructures (NPs, nanoprecipitates, and nanotwins) and dislocations. A calculated efficiency of ∼9.3% and an average ZT of 0.63 also reveal the potential application of tetrahedrite at medium temperatures. Additionally, the mechanical properties are improved because of a second phase strengthening and nanotwin structures.
Keywords: dislocation; magnetic γ-Fe2O3; nanostructure engineering; tetrahedrite; thermoelectric.