Formation of Cu3Se2 and Ag2Se by sonochemical solid-state reactions at room temperature

We reported previously that copper and silver chalcogenides were formed by interparticle collisions induced by ultrasonic irradiation. Here the formation of Cu3Se2 and α-Ag2Se is reported in more detail. The elemental mixture with stoichiometric ratio immersed in methanol was irradiated with ultrasound at 28 kHz at room temperature using a commercial ultrasonic cleaner. Scanning electron microscopy (SEM) observations for (3Cu+2Se) and (2Ag+Se) systems showed that the reactions proceeded from the surface to the inside of each particle of Cu (or Ag) and Se, exhibiting a clear boundary between reacted and pure elemental region.