Simultaneous enhancement of mechanical and thermoelectric properties of Ag2Te via in-situ formed nanoprecipitate under high-pressure

State-of-the-art thermoelectric devices require materials that combine excellent mechanical and thermoelectric properties, and the reinforcement by dispersion of nanoprecipitates is regarded as a promising solution. However, the process of introducing nanoprecipitates into materials usually involves complicated procedures. This paper presents a comparative analysis of high-pressure (HP), Spark Plasma Sintering (SPS), and melting (M) methods for preparing Ag 2 Te bulk samples. In particular, the HP method can introduce abundant nanoprecipitates at the grain boundary of Ag 2 Te bulk samples. The dispersion of nanoprecipitates significantly enhances the mechanical properties of the material, achieving an ultimate strength of 140 MPa and a fracture strain of 7.6 % through the mechanisms of crack deflection and particle pull-out. The strength and toughness of the sample improved by 57 % and 31 %, respectively, when compared to those prepared using the M method. When compared to the sample prepared using the SPS method, the improvements in strength and toughness are 13 % and 111 %, respectively. The energy filtering effect of the nanoprecipitates also improved the effective mass and Seebeck coefficient of the sample. In addition, the sample prepared by HP method exhibits higher carrier concentration due to minor Ag loss in the lattice at low temperature and without any applied current. Ultimately, in the temperature range of 300–405 K, the Ag 2 Te-HP sample has an average ZT value of 0.53, which is 110 % higher than that of Ag 2 Te-SPS sample and 200 % higher than that of the Ag 2 Te-M sample.