Rational Design of Entropy-Driven AgSnSbTe3 with Enhanced Thermoelectric Efficiency Index for Sustainable Waste Heat Recovery

Abstract

Entropy-driven alloying has emerged as an innovative approach for synthesizing high-performance thermoelectric materials. This study explores the influence of processing conditions on the structural, mechanical, and transport properties of AgSnSbTe3, a cation-disordered entropy-stabilised alloy of AgSbTe2 and SnTe, providing a detailed comparison with existing literature. Modifications in the synthesis route led to intrinsic variations in transport properties, and this study provides an in-depth scientific analysis to demonstrate how these variations in processing steps directly influences the transport properties. Unlike previous studies that used annealing or spark plasma sintering for fabricating AgSnSbTe3, this work adopts a simple melt-processing route without post-processing. Despite this, an impressive thermoelectric figure of merit, zT ∼ 0.8 at 673 K is achieved, with reduced processing time and energy consumption for material fabrication. In this work, the "Thermoelectric Efficiency Index" (TEI) is proposed to integrate thermoelectric performance (zT) with processability factors, including processing time and energy consumption for material fabrication, to assess the feasibility of a material (performance) and its synthesizability/processing conditions (time and energy) for commercial applications and sustainable manufacturing. The proposed synthesis approach achieves a significantly higher TEI (∼ 250%) compared to previous studies, thus making it a more viable route for real-time industrial applications. This research underscores the necessity of balancing material efficiency, processability, and energy consumption to achieve realistic and energy-efficient solutions for thermoelectric waste heat recovery. From a scientific standpoint, this work also enlightens the anharmonic contributions to phonon scattering, a phenomenon attributed to cation disordering in the entropy-stabilised structure.