Thermal expansion anomalies at high temperatures near stoichiometric Zn4Sb3 composition

Thermal analysis by differential scanning calorimetry (DSC) and thermal expansion measurement have been performed between room temperature and 873 K on near stoichiometric Zn4Sb3Zn4Sb3 compounds prepared by a gradient freeze method with various starting compositions. It has been revealed that there is a strong correlation between the anomalies observed both in the DSC profile and thermal expansion and the existence of a segregated Zn impurity phase. Impurity-free sample shows a large linear expansion jump of 0.3% at 767 K. The samples including an impurity of Zn show a huge linear expansion jump of 1% associated with an endothermic reaction, due to the formation of the Zn3Sb2Zn3Sb2 phase at 686 K.