Thermoelectric properties of Zn4Sb3 preparedby mechanical alloying
Il-Ho Kim, Soon-Chul Ur
Dept. of Materials Science andEngineering/Nano Technology Laboratory, Chungju National University, Chungju,Chungbuk, 380-702, Korea
Zn4Sb3 hasemerged as one of the most promising thermoelectric materials, since it shows ahigh figure of merit value in an intermediate temperature range (450-650K). Itis very common for Zn-Sb systems that a large number of macroscopic andmicroscopic cracks as well as occasional bubbles are found due to thevolumetric changes during the phase transition at high temperature. Otherdifficulties in preparation process are compositional changes and poor tendencyto form thermoelectric Zn4Sb3 because it decomposes intoZnSb and Zn at high temperature due to the relatively poor stability of thecompound. As one of the solid state syntheses, mechanical alloying of elementalZn and Sb powders followed by hot pressing is considered in this study. Sincesome compositional changes are expected due to the evaporation of Zn, Zn richcompositions as well as stoichiometric composition to compensate for Znevaporation are considered. The effects of milling time, Zn addition and hotpressing conditions on the formation of Zn4Sb3 phase areinvestigated. Phase transformations during mechanical alloying aresystematically investigated using XRD and SEM. Thermoelectric properties areevaluated for the hot pressed specimens and their temperature dependences arealso investigated.