Repairable Characteristic of Zn4Sb3 and Its Influence on Thermoelectric Performance

Thermoelectric materials inevitably experience performance degradation and lose their value after a long period of use. A means of repairing damaged thermoelectric materials would help extend their service life. Zn4Sb3 is a promising thermoelectric material at medium temperatures, but its stability is controversial. We observed that Zn4Sb3 partially decomposed into ZnSb and Zn after heat treatment at 523 K for 5 h. Zn ions migrated to the grain boundaries and precipitated as metallic Zn. The removal of Zn caused a large amount of nano-ZnSb to appear in the crystal grains. The scattering of phonons by nano-ZnSb and metallic Zn improved the thermoelectric performance of the Zn4Sb3 composites. After a further 5 h of heat treatment at a higher temperature of 623 K, the partially decomposed Zn4Sb3 returned to its undecomposed state. Both nano-ZnSb and metallic Zn disappeared, and the Zn4Sb3 sample recovered from a multiphase to a single-phase system. The thermoelectric performance was almost the same as before the heat treatment. Molecular dynamics simulations revealed that this repairability originates from the reversible migration of Zn. The increased potential energy powers the lattice contraction, and the force driving the lattice contraction also drives the reverse migration of Zn. The high diffusion rate of Zn(2) atoms shortens the repair process. This repairable feature of Zn4Sb3 allows it to switch flexibly between performance and stability. The reversible migration of Zn gives Zn4Sb3 the potential to be used in a solid-state battery.

Automated summary

The researchers discovered that Zn4Sb3 material can be repaired in terms of its thermoelectric performance and stability through the reversible migration of Zn ions under certain conditions, providing flexibility for its various applications.