Realization of strain field origination via Sb substitution in naumannite Ag₂Se for room temperature power generation

Silver selenide (Ag₂Se) is considered as an excellent candidate to alter n-type Bi₂Te₃ for near-room-temperature thermoelectric applications owing to its distinctive transport properties, such as glass like thermal conductivity and intrinsically high electrical conductivity. This report summarizes the enhanced thermoelectric properties of Ag₂Se via Antimony (Sb) incorporation. In this study, an energy and time efficient mechanical alloying process followed by hot press technique has been adopted to synthesize Ag_2-xSb_xSe (x = 0, 0.01, 0.02 & 0.03) samples. The XRD patterns confirmed the formation of orthorhombic structure of Ag₂Se. The TG–DTA revealed the thermodynamic stability and the phase transition from semiconducting nature to superionic conducting nature of Ag₂Se. The Sb substitution significantly improved the electrical transport properties and consequentially reduced the thermal transport properties, leads to the improved thermoelectric properties of Ag₂Se. The enhanced electrical conductivity and Seebeck coefficient leads to a high-power factor of 925 µWm⁻¹K⁻² at 393 K for x = 0.01 sample. The effective scattering of phonons triggered by crystal imperfections due to Sb incorporation aids to obtain a low thermal conductivity of 0.8 W/mK. A maximum zT of 0.34 is obtained at 393 K for Ag_2-xSb_xSe sample with x = 0.02 via simultaneous modulation of electrical and thermal transport properties. The results indicates that, thermoelectric properties of Ag₂Se can be improved through semi-metal incorporation.