Thermoelectric Properties of Non-Stoichiometric β-Zn_{3.83 + δ}Sb₃ Polycrystals Sintered by a Hot-Press Method

Abstract

In a moderate temperature range (450–650 K), β-Zn3.83 + δSb3 has numerous advantages because the figure-of-merit (Z T) of β-Zn3.83 + δSb3 is the highest in this temperature range. However there are difficulties when attempting to control the stoichiometry so as to manufacture Zn3.83 + δSb3 specimens. In this study, three different compositions, Zn3.83Sb3 [δ (excess Zn) = 0], Zn3.9Sb3 (δ= 0.07), and Zn4Sb3 (δ= 0.17), were designed to obtain a β-Zn3.83 + δSb3 single phase through a hot-press sintering process. An investigation for the temperature dependence of thermoelectric properties confirmed that the Zn4Sb3 (δ= 0.17) composition hot-pressed at 723 K was the optimized condition for obtaining the Zn3.83 + δSb3 single phase representing best thermoelectric properties. As a result, a maximum Z T value of 1.33 was obtained at a measuring temperature of 664 K for the Zn4Sb3 (δ= 0.17) composition hot-pressed at 723 K.