Preparation of Single Phase β-Zn₄Sb₃ Thermoelectric Materials by Mechanical Grinding Process

Abstract

Single phase β-Zn₄Sb₃ was prepared by mechanical grinding (MG). Source materials for the Zn₄Sb₃ ingots were prepared using three different processes after the direct melting of constituent elements. The ingot was obtained by quenching the melt in water within an evacuated quartz ampoule and heat-treated for a total of 200 h in two stages at 723 K and 673 K. The resultant ingots were mechanically ground and sintered at 623 K by hot pressing. The sintered materials were obtained crack-free single phase β-Zn₄Sb₃ and characterized by X-ray diffraction, differential thermal analysis (DTA) and thermoelectric property measurements. The thermal conductivity of the sintered materials was 0.88 Wm⁻¹K⁻¹ at room temperature and this was slightly lower than that reported for the materials prepared by a conventional method. Results indicate that the β-Zn₄Sb₃ single phase of the dimensionless figure of merit ranged from 1.06–1.31 at 573 K.