Thermoelectric and mechanical properties of ZnSb/SiC nanocomposites

Intermetallic compound ZnSb is a promising thermoelectric (TE) material with the advantages of low toxicity, abundance, and low cost; however, the relatively low figure of merit ZT and the brittleness of ZnSb limit its applications in TE devices. In this study, ZnSb/SiC nanocomposites were synthesized in order to improve both the TE and mechanical properties of ZnSb. ZnSb-based nanocomposites with x vol% SiC nanoparticles (x = 0, 0.3, 0.5, and 0.7) were prepared by mechanical alloying and spark plasma sintering. The power factor of ZnSb/SiC nanocomposite with 0.3 vol% SiC is increased. The thermal conductivity of all ZnSb/SiC nanocomposites is decreased due to the increase of interface scattering for phonons. More importantly, the fracture toughness of the nanocomposites is enhanced due to the addition of SiC. The largest ZT value and fracture toughness are found in the sample with 0.7 vol% SiC. The maximum ZT value of 0.68 is obtained at 400 °C, which is 35 % higher than that of the reference sample without SiC. The largest fracture toughness is 0.64 MPa m^1/2, which is 31 % larger than that of the reference sample. The experimental data demonstrate that ZnSb/SiC nanocomposites with simultaneous enhancement of TE and mechanical properties are favorable for practical TE applications.