Entropy-mediated phase stabilization and transport optimization for high-performance n-type AgBiTe₂ thermoelectrics

The practical application of AgBiTe₂, a promising thermoelectric candidate with intrinsically low thermal conductivity, is hindered by the thermodynamic instability of its cubic phase. In this work, we propose an entropy-engineering strategy via PbTe alloying to stabilize the cubic phase over the operating temperature range. Building upon this robust matrix, we employ Cd incorporation to optimize the thermoelectric transport properties. Specifically, Cd doping effectively optimizes the n-type carrier concentration while concurrently improving the Seebeck coefficient, suggesting a possible modification of the electronic structure. Microstructurally, Cd supersaturation induces a hierarchical defect architecture comprising Cd-enriched inclusions and dense dislocations. These multiscale features, integrated with intrinsic cation disorder, synergistically scatter phonons. Consequently, the optimized (AgBi_0.94Cd_0.06Te₂)_0.6(PbTe)_0.4 achieves a peak zT of ∼0.51 at 632 K. This performance represents a ∼143% enhancement over state-of-the-art n-type AgBiTe₂-based counterparts, establishing entropy-mediated stabilization as a viable route for advancing high-performance thermoelectric materials.