Decreased order-disorder transition temperature and enhanced phonon scattering in Ag-alloyed Cu3SbSe3

Cu3SbSe3 is a promising thermoelectric material with ultralow lattice thermal conductivity, especially at temperatures above 450 K at which the order-disorder transition of copper ions takes place. To investigate whether the high-temperature disordered phase can be extended to lower temperature, a series of Ag-alloyed Cu3-xAgxSbSe3 (x = 0, 0.1, 0.2 and 0.3) polycrystalline samples were synthesized and characterized in this work. It was found that the Ag-alloying shifts the order-disorder transition temperature to lower ones, which is beneficial to the thermoelectric application of Cu3SbSe3. For thermal transport, Ag-alloying is effective in suppressing lattice thermal conductivity in the copper-ions-ordered region, while in the copper-ions-disordered region, Ag-alloying barely has any effect on lattice thermal conductivity, as the phonon scattering is dominated by the liquid-like behavior of copper ions. Although Ag and Cu atoms have the same valence electron number, the carrier concentration is slightly increased after Ag-alloying, which suppresses the bipolar effect and increases the Seebeck coefficient at high temperatures. Finally, a maximum zT of 0.34 is obtained at 652 K for the sample Cu2.7Ag0.3SbSe3, which is 161% higher than that of the pristine sample. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The high-temperature disordered phase of Cu3SbSe3 can be extended to lower temperatures by alloying with Ag, which effectively suppresses the lattice thermal conductivity and increases the Seebeck coefficient at high temperatures. Ag-alloying has a significant impact on the thermal and electrical properties of Cu3SbSe3.