The nanocrystalline thermoelectric compound Bi2Te3 forms by a particle-wise explosive reaction during mechanical alloying

During mechanical alloying to synthesize the nanocrystalline thermoelectric compound Bi2Te3, the reaction from elemental constituents occurs in only 15 min. Using X-ray diffraction and quantitative metallography, the mechanism for this rapid transformation is identified as Te and Bi powders reacting explosively on a particle-by-particle basis. The reaction is apparently ignited by local heat release from milling tool collisions, and sustained by the heat of compound formation only over the scale of individual particles.