Comparison of thermoelectric performance of AgPbxSbTe20 (x = 20–22.5) polycrystals fabricated by different methods

Both vacuum melting and mechanical alloying (MA) were applied to the fabrication of AgPbxSbTe20 (x = 20, 21 and 22.5) as a promising thermoelectric material to investigate the processing influence on its thermoelectric properties. The AgPbxSbTe20 compound powders were prepared by pulverizing the melted ingots or directly from MA, which were then consolidated to fine-grained bulk materials by spark plasma sintering (SPS). A high ZT value of 1.25 at 725 K was observed in the AgPb20SbTe20 samples fabricated by both methods. Thermoelectric properties of all AgPbxSbTe20 compounds synthesized by vacuum melting method are nearly the same as that of those fabricated by MA combined with SPS in the whole measured temperature range. Considering the complexity of the melting method but with the same results as the MA–SPS method, the present work revealed that the MA–SPS process is more suitable for the fabrication of PbTe-based thermoelectric materials.

► Thermoelectric AgPbxSbTe20 alloys were fabricated by two methods to clarify processing influence.
► Comparison with melting process confirmed the merits of MA-SPS process for fabricating AgPb20SbTe20.
► Thermoelectric property of AgPbxSbTe20 was revealed more sensitive to Pb content rather than process.
► A dimensionless figure of merit up to 1.25 at 725K was obtained in an optimal composition AgPb20SbTe20.