Thermoelectric Properties of Melt-Spun Zn x Sb 3 Ribbons

Abstract

Melt-spun ribbons composed of Zn_xSb₃ (3.4 ≤ x ≤ 4.3) were fabricated through a single-wheel melt-spinning process at wheel velocities of 0.6 m s⁻¹ to 4.2 m s⁻¹ and annealed for 2 h at 673 K. The structures were investigated using x-ray diffraction. The dimensionless figure of merit ZT, Seebeck coefficient, and electrical conductivity were measured to estimate the power factor and thermal conductivity. β-Zn₄Sb₃ in the as-spun ribbons 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. The Seebeck coefficient in the as-spun and annealed ribbons tended to decrease slightly with increasing x at all the wheel velocities. At 0.6 m s⁻¹, the ZT and power factor of as-spun and annealed ribbons increased with increasing x at x < 4.0 because of increase in the electrical conductivity. At 4.2 m s⁻¹, ZT was smaller than that at 0.6 m s⁻¹ because the electrical conductivity was small in the as-spun ribbons and the thermal conductivity was large in the annealed ribbons.