Effect of Open Die Pressing on chemical-physical properties of Zn4Sb3 compound

Recently, semiconducting intermetallic compounds, belonging to the Zintl's Phases, have attracted much attention due to their unexpectedly low thermal conductivity, which leads to improved thermoelectric properties. The glass-like thermal conductivity of Zn4Sb3, originated in the framework Zn position of its structure, make this compound one of the most studied phases in the thermoelectric field. The reduction of grain size obtained by the melt spinning process can lead to an improvement of Figure of the Merit-ZT but, unluckily, is associated with an increase of material brittleness. As a prosecution of a previous work, melt spun samples and powders obtained by a solid-phase synthesis of Zn4Sb3 were sintered by Open Die Pressing (ODP) process: with this technique, already used for sintering of nano-powder of chalcogenides, bulk samples with high density and compactness were produced. Chemical physical properties and the stability of the pure ?-phase Zn4Sb3 are investigated after ODP process. All samples were studied in terms of crystal structure, phases composition, thermal stability, mechanical resistance and thermoelectric properties. Preliminary results show the formation of ZnSb phase into the ?-Zn4Sb3 matrix after both, melt spinning and ODP processes: the effects of time and temperature parameters of ODP process on ZnSb phase formation has also been investigated and thermoelectric properties have been compared for the different conditions.