ICT2014 Abstracts

Mg₂Si_1-xSn_x is a kind of promising thermoelectric materials used for intermediate temperature power generation, consisting of earth-abundant and non-toxic elements with low cost. Mg_2.16(Si_0.3Sn_0.7)_0.98Sb_0.02 is an extraordinary one with excellent thermoelectric properties for Mg₂Si_1-xSn_x. A lot of research results shows that nano-precipitates in Mg-Si-Sn solid solutions have been observed. However, very little work has been done on the correlation between the nano-precipitate and thermoelectric properties. In this study, a series of Mg_2.16(Si_0.3Sn_0.7)_0.98Sb_0.02 specimens have been prepared by mortar milling, solid state reaction, annealing, and plasma activated sintering (PAS) technique with different annealing processing. Although all bulks were identified as single phase by the X-ray diffraction which is consistent with the results obtained by some other researchers, many nano-precipitates inclusions were observed by FESEM and TEM in our samples. The composition, size and homogeneity of nano-precipitates can be modified by adjusting the annealing temperature. When annealing temperature is 1130K, nano composite with a finer homogeneously-distributed nano-inclusion is obtained in comparison with those samples annealed at 900 K. Thus the thermal conductivity was decreased by ~10%，while the power factor was basically unchanged, which lead to a higher dimensionless figure of merit.