Effect of Zn atomic diffusion due to pulsed electric field treatment on the thermoelectric properties of Zn–Sb films

Abstract

Zn4Sb3 has brought into sharp focus by its low cost and excellent thermoelectric (TE) properties in the medium temperature range. Zn atoms can diffuse in the Zn4Sb3 matrix under the treatment of temperature or current. This provides a way to control its TE performance. In this study, the TE properties of the Zn4Sb3 films were improved by the Zn atomic diffusion under the treatment of periodic pulsed electric field. The Zn atomic diffusion is caused by the electrostatic interaction of the pulsed electric field and the diffusion mode is related to the pulse period. When the pulse period is smaller than 10 s, the interstitial Zn atom diffuses first. The Zn vacancy increases, leading to the increase of the carrier concentration and the decrease of the resistivity. When the pulse period increases to 100 s, more Zn(1) atoms diffuse through the interstitial position, resulting in a small amount of ZnSb phase. Thereby in the Zn4Sb3 films, the carrier concentration decreases and the Seebeck coefficient increases. This kind of the synergistic effect decreases the resistivity and increases the Seebeck coefficient. The power factor of the Zn4Sb3 films treated with a pulse period of 100 s is more than 4500 μW m−1 K−2 in the range of 373 K–573 K. This study presents a new method to control atomic diffusion by periodic pulsed electric field, and the TE properties of the Zn4Sb3 films are improved.