Preparation and Thermoelectric Properties of Polycrystalline In4Sn3−x by Mechanical Alloying and Hot Pressing

Polycrystalline In4Se3−x thermoelectric materials were prepared by a combined process of mechanical alloying and hot pressing (MA-HP), and the effect of Se deficiency on their thermoelectric properties was studied. Starting from elemental In and Se powders, In4Se3 compound was synthesized after mechanical alloying for 1 h. Single-phase In4Se3 compound was obtained in the sample without Se deficiency, while some In impurity was detected in Se-deficient samples. With increasing Se deficiency x, the carrier concentration n increased, and the electrical resistivity and absolute value of Seebeck coefficient of In4Se3−x decreased rapidly. All of the In4Se3−x samples (x > 0) had higher ZT than the stoichiometric In4Se3, with In4Se2.65 showing the highest ZT because of its low thermal conductivity. The maximum ZT reached 0.93 at 700 K.