For further thermoelectric performance enhancement by the nanocomposite effect, a small amount (<2 vol. %) of 30 nm SiC particles were added into a compositionally optimized AgPb m SbTe mþ2 thermoelectric alloy fabricated by mechanical alloying and spark plasma sintering. Although the energy filtering effect is not available in the present composite due to the mismatched interface between SiC and the matrix, a small amount of SiC dispersions were revealed to be effective to reduce the thermal conductivity via enhancing phonon scattering. A high figure of merit up to 1.54 at 723 K was obtained in the AgPb m SbTe mþ2 matrix composite containing 1 vol. % SiC nanoparticles. V C 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4869220] Thermoelectric materials have drawn increasing attention because of their potential in energy harvesting and electronic cooling device applications. 1-3 The efficiency of thermoelectric conversion depends on the dimensionless figure of merit, ZT, defined as ZT ¼ a 2 (qj) À1 T, where a is the Seebeck coefficient (also called as thermopower), T is the absolute temperature, q is the electrical resistivity, and j is the thermal conductivity, 4 respectively. It is not easy to independently control these parameters to improve the ZT value because of the coupling relationship among a, q, and j. In last ten years, nanostructuring in the form of quantum well, 5 superlattice, 6 nanodot, 7,8 as well as nanostructured bulk composites 9,10 have shed new light on the improvement of thermoelectric materials, where they can significantly reduce thermal conductivity without affecting electrical properties, even improvement in some cases. Enhanced thermoelectric performance in many materials with ZT > 1 or ZT % 1 has been reported, such as Bi 2 Te 3 , 11,12 PbTe/PbS, 13-15 and oxide compounds. 16 Especially, in PbTe-based AgPb m SbTe mþ2 (LAST, lead-antimony-silver-tellurium) compounds, a high ZT value up to 1.7 at 700 K was achieved by Hsu et al. in 2004. 17 Previous studies 9,17,18 indicated that the endotaxial nanostructure is very effective in enhancing ZT value of LAST alloys, such as the phase-segregation with the presence of embedded nanodots (appear to be rich in Ag and Sb) in the PbTe matrix, which are believed to play an important role in scattering phonons without influencing electron transport meanwhile. However, one may worry about the stability of such a nanostructure when used for a long time at high temperatures. Alternatively, intentionally mixing inert nanoparticles into a thermoelectric matrix should be an easier approach to create composites, which should have more difficulty to grow or coalesce than the in situ precipitates formed by annealing. In fact, it is demonstrated that mixing SiC nanoparticles into the BiSbTe matrix can effectively enhance its thermoelectric and mechanical properties. 19,20 In this work, we explored the effect of incorporating nano-SiC particles in the LAST matrix on the TE properties. The atoms of Si and C are much lighter than those of Pb and Te as t...