Mechanical Alloying for Making Thermoelectric Compounds

An economical room-temperature mechanical alloying process has been shown to be an effective means of making a homogeneous powder that can be hot-pressed to synthesize a thermoelectric material having reproducible chemical composition. The thermoelectric materials to which the technique has thus far been applied with success include rare-earth chalcogenides [La3–xTe4 (0 < x < 0.33) and La3–xYbyTe4 (0 < x < 1, 0 < y < 1)] and Zintl compounds (including Yb14MnSb11 and Yb14BiSb11). The synthesis of a given material consists of the room-temperature thermomechanical- alloying process followed by a hot-pressing process. Relative to synthesis of nominally the same material by a traditional process that includes hot melting, this synthesis is simpler and yields a material having superior thermoelectric properties.