Synergistic Optimization of the Electronic and Phonon Transports of N-Type Argyrodite Ag8Sn1-xGaxSe6 (x=0-0.6) through Entropy Engineering

The argyrodite compound, Ag8SnSe6 (ATS), which is one of the promising thermoelectric (TE) candidates, is receiving growing attention in thermoelectrics recently. However, its TE performance is still low and phases are unstable as the temperature varies. In this work, inspired by entropy engineering, we eliminate the beta/gamma phase transformation at similar to 355 K via alloying Ga, thus extending its high-temperature cubic phase from 320 to 730 K. In the meantime, the power factor (PF) enhances by 10% and lattice thermal conductivity (kappa(L)) reduces by 40% at 723 K. As a result, the ZT value is boosted to similar to 1.15 for Ag8Sn0.5Ga0.5Se6, which stands high among the ATS systems. This proves that the entropy engineering is an effective approach to extend the high-temperature range for the cubic gamma-phase and improve its TE performance simultaneously.

Automated summary

By alloying with gallium, the phase transformation in the argyrodite compound can be eliminated, extending its high-temperature cubic phase range and improving its thermoelectric performance. The power factor increases, and the lattice thermal conductivity decreases as a result.