EFFECT OF CAVITATION CONDITIONS ON AMORPHOUS METAL SYNTHESIS

Acoustic cavitation is an effective means of concentrating energy and can be used to drive a variety of chemical reactions. By changing the experimental parameters that control conditions during bubble collapse, different chemical environments can be created. The sonochemical reactions associated with metal carbonyls in alkane solvents are quite diverse and illustrate this phenomena. For example, ultrasonic irradiation of iron pentacarbonyl (Fe(CO)5) under weak cavitation conditions initiates ligand substitution and cluster formation reactions. In contrast, under conditions that maximize the cavitational heating (for example, Ar, low vapour pressures, low ambient temperatures), the primary Fe(CO)5 reaction is metal powder formation. The powder synthesized during sonolysis is amorphous and has unusual magnetic and catalytic properties. This amorphous iron powder is formed from the enormous heating and cooling rates generated during acoustic cavitation.