IMPROVEMENT OF THERMOELECTRIC PROPERTIES IN ZN-SB ALLOYS

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The aim of the research is to improve micro-structures and thermoelectric properties in ZnxSb3 (x = 3.4-4.3) alloys for generating power by directly converting heat into electricity.The alloys were fabricated through a single-wheel melt-spinning process at wheel velocities of 0.6-4.2 m s-1. The micro-structures were investigated using X-ray diffraction, transmission electron microscopy, together with energy dispersive X-ray analysis, and by calculating free energy. β-Zn4Sb3 in the as-spun state coexisted with ZnSb or Zn at 0.6 m s-1, while it coexisted with ζ-Zn3Sb2 in x >= 3.8 at 4.2 m s-1, where ζ-Zn3Sb2 disappeared in the annealed ribbons. Nano-scale voids and zinc inclusions precipitatedor disappeared through reactions of zinc vacancies, interstitial zinc atoms, and zinc atoms in β-Zn4Sb3.The dimensionless figure of merit, power factor, Seebeck coefficient, electrical conductivity and thermal conductivity which were measured depended on the complex micro-structures of β-Zn4Sb3 which were peculiar to the fabrication processes.