ABSTRACT
Mechanochemistry, fi rst defi ned by Ostwald 1 at the beginning of the twentieth century, deals with an interplay between mechanical energy and chemical states of matters. Early mechanochemical studies were focused on the chemical transformation induced by gravitational and kinetic energy, as well as energies stored in solids. Mechanochemical phenomena were then broadly divided into two categories: those related with chemical reactions per se, or those dealing with the change in the activity or reactivity of solids. These are called mechanochemical reactions and mechanical activation, respectively. The boundary between these subdivisions is diffuse, however, since both of them involve common physicochemical changes of solids under the infl uence of mechanical energy.
